This is a list of missing civil parishes, it was drawn up in 2014, with subsequent additions and was derived from many sources, there are probably some that aren't actually CPs, or are just alternative names.
Aldborough and Thurgarton (same as Aldborough & Thurgarton)
Ashton Hayes and Horton-cum-Peel
Bandleyside (partly exists) (just a parish council http://www.cwherald.com/a/archive/25-years-orton.280567.html)
Bishop Thornton, Shaw Mills and Warsill
Bottesford (town) (exists)
Brandon Parva, Coston, Runhall and Welborne
Brant Broughton and Stragglethorpe
Broughton Hamlet (exists)
Bull Fort (apparently no longer a CP per Talk:Civil parishes in Cornwall from after 1974)
Burgh le Marsh (town) (exists)
Caistor (town) (exists)
Campbell Park (parish) (exists)
Cantley, Limpenhoe and Southwood
Careby, Aunby and Holywell (exists)
Carlton le Moorland (exists)
Carrington and New Bolingbroke
Castle Carrock and Geltsdale (partly exists) (Castle Carrock is a separate parish, Geltsdale appears not to be a parish anymore)
Checkley, Staffordshire (exists)
Cley Next The Sea (exists)
Coningsby (town) (exists)
Cotton, Staffordshire Moorlands (Cotton, Staffordshire is different to Coton, Staffordshire https://en.wiki.x.io/w/index.php?title=Cotton,_Staffordshire&diff=prev&oldid=552215929) (exists)
Cranwell and Byard's Leap (maybe same as Cranwell, Brauncewell and Byard's Leap)
Cranwell & Byards Leap (same as Cranwell and Byard's Leap)
Cranwell, Brauncewell and Byard's Leap
Cranwell, Byards Leap & Brauncewell (same as Cranwell, Brauncewell and Byard's Leap)
Creeting St Peter or West Creeting (same as Creeting St. Peter or West Creeting)
Crichel (parish) (exists)
Drakes Broughton and Wadborough
Dunham-on-the-Hill and Hapsford
Eastleigh Town (exists)
Eastville, Linconlshire (exists) (typo of dab (Lincolnshire), Eastville, Lincolnshire)
Ellerton Abbey (parish) (exists)
Evenlode, Gloucestershire (exists)
Fairfields, Buckinghamshire (exists)
Forcett and Carkin (no longer a parish)
Fylingdales Moor (same as Lands common to Fylingdales and Hawsker-cum-Stainsacre)
Gainsborough (town) (exists)
Garton, East Riding of Yorkshire
Garvestone, Reymerston and Thuxton
Gayton Le Marsh (exists)
Gayton Le Wold (exists)
Grange De Lings (exists)
Grimston, Saxelbye and Shoby (partly exists) (maybe not a parish, Grimston, Leicestershire is a separate parish according to Pastscape)
Hadley and Leegomery (same as Hadley & Leegomery)
Hamsterley Common (same as Land common to Hamsterley, Lynesack and Softley and South Bedburn)
Hill, South Gloucestershire (exists)
Hinton-in-the Hedges (exists)
Holbrook Farm, Wiltshire (same as Lands common to the parishes of Broughton Gifford and Melksham Without, Holbrook Farm appears to only be used on Wikipedia)
Holme Next the Sea (exists)
Holton Le Moor (exists)
Holywell cum Needingworth (same as Holywell-cum-Needingworth)
Horncastle (town) (exists)
Hough on the Hill (exists)
Houghton Le Side (exists)
Hutton-Sessay (exists)
Ilton-cum-Pott (Ilton cum Pott is a redirect)
Immingham (town) (exists)
Isle of Man, Devon (same as Lands common to Axminster and Kilmington, Isle of Man appears to only be used on Wikipedia)
Kettering Town (parish) (OS only shows it covering a small area east of the town)
Kimbolton and Stonely (partly exists) (Kimbolton, Cambridgeshire is apparently a separate parish even though name apparently changed in 2003)
Kingston Near Lewes (exists)
Kingston Russell (parish) (exists)
Kirkby La Thorpe (exists)
Kirkby Mallory, Peckleton and Stapleton
Kirkby Wharfe with North Milford
Kirmond Le Mire (exists)
Land common to Hamsterley, Lynesack and Softley and South Bedburn
Lands cmn to the parishes of Brancepeth and Brandon and Byshottles
Lands Common to Axminster and Kilmington (exists)
Lands Common to Axminster and Kilmington C.P.s (exists)
Lands Common to Axminster and Kilmington C.P. s (exists)
Lands common to Bridestowe and Sourton CP's (exists)
Lands common to Fylingdales and Hawsker-cum-Stainsacre
Lands common to Holme Abbey, Holme Low and Holme St Cuthbert
Lands Common to Holme Abbey, Holme Low and Holme St Cuthbert (same as Lands common to Holme Abbey, Holme Low and Holme St Cuthbert)
Lands common to the Parishes of Axminster and Kilmington (exists)
Lands common to the Parishes of Bridestowe and Sourton, Landulph
Lands common to the parishes of Broughton Gifford and Melksham Without (same as Lands common to the parishes of Broughton Gifford and Melksham without)
Lands common to the parishes of Broughton Gifford and Melksham without
Langton By Spilsby (exists)
Langton By Wragby (exists)
LCPs of Brancepeth and Brandon and Byshottles (same as Lands cmn to the parishes of Brancepeth and Brandon and Byshottles)
LCPs of Broughton Gifford and Melksham Without (same as Lands common to the parishes of Broughton Gifford and Melksham without)
LCPs of Fylingdales and Hawsker-cum-Stainsacre (same as Lands common to Fylingdales and Hawsker-cum-Stainsacre)
LCPs of Hamsterley, Lynesack and Softley, and South Bedburn (same as Land common to Hamsterley, Lynesack and Softley and South Bedburn)
LCPs of Holme Abbey, Holme Low and Holme St Cuthbert (same as Lands common to Holme Abbey, Holme Low and Holme St Cuthbert)
LCPs of Stanhope, Wolsingham and Tow Law (same as Wolsingham Park Moor lands cmn to Stanhope, Tow Law and Wolsingham)
Lea Hall, Derbyshire (not a parish anymore)
Leek Wootton and Guys Cliffe (exists)
Lenton Keisby and Osgodby (exists)
Lilleshall and Donnington (now Lilleshall, Donnington and Muxton)
Lilleshall, Donnington and Muxton
Lindrick with Studley Royal and Fountains
Linton, Bringsty (exists)
Little Hadham, Hertfordshire (exists)
Loughton & Great Holm (exists)
Louth (town) (exists)
Mablethorpe and Sutton (town) (exists)
Mareham Le Fen (exists)
Market Deeping (town) (exists)
Market Rasen (town) (exists)
Marston, Staffordshire (exists)
Middleton, East Riding of Yorkshire
Milstead and Kingsdown (no longer exists)
Morton, South Kesteven (now Morton & Hanthorpe)
Morton & Hanthorpe (exists)
Newbold Pacey and Ashborne (partly exists) (not a CP)
Newton By Malpas (exists)
Newton-on-the-Moor and Swarland
Normanby By Spital (exists)
Normanby Le Wold (exists)
Normanton Le Heath (exists)
Normanton on the Wolds (exists)
North Hykeham (town) (exists)
Norton and Lenwick (does it exist?, maybe actually Norton and Lenchwick)
Oldbury-upon-Severn (exists)
Old Hutton and Homescales (same as Old Hutton and Holmescales, typo)
Osmotherly (exists) (same as Osmotherley, Cumbria, typo)
Outseats (no longer a parish)
Preston, Dover (exists)
Radbourne, Warwickshire (same as Radbourn, Warwickshire)
Scalthwaitrigg (exists) (same as Scalthwaiterigg, typo)
Shelford and Newton (no longer a parish)
Shotton (parish) (same as Shotton (parish, near Peterlee)
Shotton (parish, near Peterlee)
Sixpenny Handley and Pentridge
Skegness (town) (exists)
Skidbrooke with Saltfleet Haven
Skinburness Marsh (same as Lands Common to Holme Abbey, Holme Low and Holme St Cuthbert)
Slanford with Orleton (maybe Stanford with Orleton?)
Slangford with Orleton (doesn't appear to exist)
Sleaford (town) (exists)
Smalley (parish) (exists)
South Cadbury and Sutton Montis
South Tedworth (not a parish anymore, see User:Morwen/parish delta) (maybe a typo of South Tidworth in the census as it is South Tidworth on the Ordnance Survey and North Tidworth is even North Tidworth in the census, see also List of civil parishes in Wiltshire where this assertion has also been made)
South Willesborough & Newtown (same as South Willesborough and Newtown)
South Willesborough and Newtown
Spilsby (town) (exists)
Stamford (town) (exists)
St. Andrews, Swindon (same as St Andrews, Swindon)
St Cosmus and St Damian in the Blean (St. Cosmus and St. Damian in the Blean is on redirects)
St. Cross, South Elmham (exists)
St. Giles on the Heath (exists)
St. Helens, Isle of Wight (exists)
St. James, South Elmham (exists)
St. John, Ilketshall (exists)
St. Lawrence, Ilketshall (exists)
St. Margarets, Herefordshire (exists)
St. Margaret's at Cliffe (exists)
St. Margaret, South Elmham (exists)
St Mary, South Elmham Otherwise Homersfield (exists)
St. Mary, South Elmham Otherwise Homersfield (exists)
St Devereux (same as St. Devereux)
St. John's Castlerigg and Wythburn (exists)
St. Michael, Hertfordshire (exists)
St. Michael, South Elmham (exists)
St. Nicholas at Wade (exists)
St. Paul Malmesbury Without (exists)
St. Peter, South Elmham (exists)
St. Weonards (exists)
Stanton on the Wolds (exists)
Staunton Coleford (exists)
Sturton By Stow (exists)
Sutton-by-Dover (exists)
Thornton Le Fen (exists)
Thorpe By Water (exists)
Tilton on the Hill and Halstead
Tiverton and Tilstone Fearnall
Tretire (appears not to be a parish)
Tritlington and West Chevington
Wainfleet All Saints (town) (exists)
Walcot near Folkingham (exists)
Walcot Near Folkingham (same as Walcot near Folkingham)
Waltham and Thorpe Arnold (same as Waltham on the Wolds and Thorpe Arnold)
Waltham on the Wolds and Thorpe Arnold
Waresley cum Tetworth (same as Waresley-cum-Tetworth)
Weather Hill Wood (same as Lands cmn to the parishes of Brancepeth and Brandon and Byshottles Weather Hill Wood appears to only be used on Wikipedia)
Wells-Next-the-Sea (exists)
Weston By Welland (exists)
Wharram, North Yorkshire (exists)
Willingham, Lincolnshire (exists)
Winterton (town) (exists)
Wolsingham Park Moor (same as Wolsingham Park Moor lands cmn to Stanhope, Tow Law and Wolsingham)
Wolsingham Park Moor lands cmn to Stanhope, Tow Law and Wolsingham
Wootton St Lawrence with Ramsdell
Wymondham and Edmondthorpe (partly exists) (apparently renamed in 2003, simply called Wymondham on OS)
Redirects
Amble By the Sea (same as Amble by the Sea)
Ardley with Fewcott (partly exists) (maybe separate parishes)
Bierton with Broughton (no longer a parish)
Blunsdon St. Andrew (same as Blunsdon St Andrew)
Broadoak, Cornwall (renamed to match village)
Brobury with Monnington on Wye
Castle Bolton with East and West Bolton
Caterham on the Hill (same as Caterham-on-the-Hill)
Chidham (not a parish anymore, now Chidham and Hambrook)
Covenham St. Mary (same as Covenham St Mary)
Creeting St. Peter or West Creeting
Dinnington St John's (same as Dinnington St. John's)
Felmersham and Radwell (partly exists) (Felmersham is a separate parish)
Foston, East Riding of Yorkshire
Hesketh with Becconsall (same as Hesketh-with-Becconsall)
Huntwick with Foulby and Nostell
Ilton cum Pott (same as Ilton-cum-Pott which is on the main list)
Kirkoswald and Renwick (partly exists) (Kirkoswald is a separate parish)
Lillingstone Dayrell with Luffield Abbey
Longwick cum Ilmer (same as Longwick-cum-Ilmer)
Mangotsfield Rural (no longer a parish, at least by this name)
Markingfield Hall (same as Markenfield Hall (parish))
Mawgan in Pydar (same as Mawgan-in-Pydar)
Menwith with Darley (now Darley and Menwith)
Newbottle and Charlton (partly exists) (Newbottle, Northamptonshire is a separate parish)
North Bedlington (!)
North Tidworth (not a parish anymore, see User:Morwen/parish delta)
Nythe (no longer a parish)
Offord Cluny and Offord D'Arcy
Paul (civil parish) (no longer a parish)
Poynton with Worth (same as Poynton-with-Worth)
Richard's Castle (Hereford) (same as Richards Castle (Hereford))
Rushden and Wallington (partly exists) (maybe separate parishes)
Shuckburgh Lower and Upper (same as Upper and Lower Shuckburgh)
Silloth on Solway (same as Silloth-on-Solway)
St Blaise, Cornwall (same as St. Blaise, Cornwall)
St Bridget Beckermet (same as St. Bridget Beckermet)
St. Cosmus and St. Damian in the Blean
St John Beckermet (same as St. John Beckermet)
St Minver Highlands (same as St. Minver Highlands)
St Minver Lowlands (same as St. Minver Lowlands)
St Nicholas Hurst (same as St. Nicholas, Hurst)
St Peter the Great County (same as St. Peter the Great County)
Steeple Gidding (no longer a parish)
Stone with Bishopstone and Hartwell
Widdrington, Northumberland (now Widdrington Village)