According to the Electoral Commission, 25 constituencies will not count the result on election night itself, but on the day after (7th May). These are:
Argyll and Bute: 122nd on the list of Conservative target seats; 65th on Labour list
Berwick upon Tweed
Blyth Valley
Broadland: 95th on the list of Labour target seats; 35th on LibDem list
Buckingham
Cheltenham: 10th on the list of Conservative target seats
Copeland: 167th on the list of Conservative target seats
Henley
Hexham: 56th on the list of Labour target seats; 77th on LibDem list
Huntingdon
Kenilworth and Southam
Lancaster and Fleetwood: 114th on the list of Conservative target seats
Morecambe and Lunesdale
North East Hampshire
Norwich North: 163rd on the list of Conservative target seats
Oxford West and Abingdon: 102nd on the list of Conservative target seats
Penrith and The Border
Saffron Walden
Skipton and Ripon
St Ives
Torridge and West Devon: 17th on the list of LibDem target seats
Wansbeck
Wantage: 50th on the list of LibDem target seats
Warwick and Leamington: 117th on the list of Conservative target seats
Westmorland and Lonsdale: 14th on the list of Conservative target seats
NB: The Thirsk & Malton election will be held on May 27th, due to the death of the UKIP candidate, John Boakes
For lists of the target seats for each party see: ukpollingreport