| # | Tower | No | Year | Materials | Maker | Trusses | Layout |
|---|
| 6451 | Occold, Suffolk, S Michael | 1 | c1699 | Timber | | 5.A | 5.7 R |
| 6452 | Ockbrook, Derbyshire, All Saints | 1 | 1890 | Cast iron | John Taylor & Co | | 3 ➔ 6 |
| 6453 | Ockbrook, Derbyshire, All Saints | 1.1 | 1926 | Cast iron | Mears & Stainbank | | 3.1 |
| 6454 | Ockley, Surrey, S Margaret | 1 | 1981 | Steel | Whitechapel Bell Foundry | | |
| 6455 | Ocle Pychard, Herefordshire, S James Gt | 2 | | Oak | | | |
| 6456 | Ocle Pychard, Herefordshire, S James Gt | 1 | | Oak | | | |
| 6457 | Odcombe, Somerset, S Peter & S Paul | 1 | 1904 | Cast iron | ? John Warner & Sons | | |
| 6458 | Oddingley, Worcestershire, S James | 1 | c1660 | Oak | | 6.A | 3.1 |
| 6459 | Oddington, Gloucestershire, S Nicholas | 8 | 1973 | Steel | Whitechapel Bell Foundry | 8.1.E | 1 |
| 6460 | Oddington, Gloucestershire, S Nicholas | 1 | 1973 | Cast iron | Whitechapel Bell Foundry | 8.3.A.h | 6.1 |
| 6461 | Oddington, Oxfordshire, S Andrew | 1 | | Oak | | | |
| 6462 | Odiham, Hampshire, All Saints | 1 | | Timber | | | 6 |
| 6463 | Offenham, Worcestershire, S Mary & S Milburgh | 1 | 1925 | Cast iron | John Taylor & Co | 8.3.C.e | 6.1 |
| 6464 | Offham, East Sussex, S Peter | 1 | | Timber | | 5.L | 1 |
| 6465 | Offley, Hertfordshire, S Mary Magd | 1 | | Oak | | | |
| 6466 | Offord Cluny, Cambridgeshire, All Saints | 1 | 1620 | Timber | | 5.H | 4.6 |
| 6467 | Offord D'Arcy, Cambridgeshire, S Peter | 2 | c1620 | Oak | | 6.S.4 | 2.X1 |
| 6468 | Offord D'Arcy, Cambridgeshire, S Peter | 1 | c1620 | Oak | | 6.S.4 | 2.X1 |
| 6469 | Offton, Suffolk, S Mary | 2 | 1959 | Cast iron | John Taylor & Co | 8.3.C.e | 6.4 |
| 6470 | Offton, Suffolk, S Mary | 1 | 1983 | Steel | John Taylor & Co | | |
| 6471 | Offton, Suffolk, S Mary | 1.1 | | | | | |
| 6472 | Offwell, Devon, S Mary V | 1 | 1952 | Cast iron | John Taylor & Co | 8.3.A.h | 6.1 |
| 6473 | Ogbourne St Andrew, Wiltshire, S Andrew | 1 | 1914 | Cast iron & timber | T Doble & Son | 7.A.a | 5.1 |
| 6474 | Ogbourne St George, Wiltshire, S George | 1 | 1923 | Cast iron & steel | Gillett & Johnston | 8.3.C.e | |
| 6475 | Okeford Fitzpaine, Dorset, S Andrew | 1 | 1906 | Cast iron | Mears & Stainbank | 8.3.A.e | 6.5 |
| 6476 | Okehampton, Devon, All Saints | 1 | 1937 | Cast iron | Gillett & Johnston | 8.3.A.m | 8.3 |
| 6477 | Okehampton, Devon, S James | 1 | | Steel | | 8.1.A | |
| 6478 | Old, Northamptonshire, S Andrew | 1 | | Timber | | 6.A & 6.B | 5.5 D |
| 6479 | Old Basing, Hampshire, S Mary | 1 | c1660 | Timber | | 5.A & 6.A | 2.X1 |
| 6480 | Old Bolingbroke, Lincolnshire, S Peter & S Paul | 1 | 1897 | Cast iron | John Taylor & Co | | 6.4 |
| 6481 | Old Brampton, Derbyshire, S Peter & S Paul | 1 | 1887 | Pine | John Taylor & Co | | 6.4 |
| 6482 | Old Clee, Lincolnshire, Holy Trinity & S Mary V | 1 | 1900 | Cast iron | John Taylor & Co | | |
| 6483 | Old Cleeve, Somerset, S Andrew | 1 | 1884 | Oak | | | |
| 6484 | Old Fletton, Cambridgeshire, S Margaret | 2 | 1953 | Cast iron | John Taylor & Co | 8.3.A.h | 2.X1 |
| 6485 | Old Fletton, Cambridgeshire, S Margaret | 1 | 1953 | Cast iron | John Taylor & Co | 8.3.A.h | 4.3 |
| 6486 | Old Hill, West Midlands, Holy Trinity | 1 | 1947 | Cast iron | Gillett & Johnston | 8.3.A.m | 8.3 |
| 6487 | Old Leake, Lincolnshire, S Mary | 1 | 1671 | Timber | | 6.B | |
| 6488 | Old Malton, North Yorkshire, S Mary V | 1 | c1880 | Timber | Local labour/guild/assn | 5.A | 3.1 |
| 6489 | Old Milverton, Warwickshire, S James | 1 | c1880 | Timber | | | |
| 6490 | Old Newton, Suffolk, S Mary | 1 | 1896 | Oak | Alfred Bowell | 6.A | 6.4 |
| 6491 | Old Radnor, Powys, Wales, S Stephen | 1 | c1799 | Oak | | | |
| 6492 | Old Swinford, West Midlands, S Mary | 2 | 1959 | Cast iron | John Taylor & Co | | |
| 6493 | Old Swinford, West Midlands, S Mary | 1 | 1959 | Cast iron | John Taylor & Co | | |
| 6494 | Old Warden, Bedfordshire, S Leonard | 1 | 1899 | Cast iron | John Taylor & Co | 8.3.C.e | 6.4 |
| 6495 | Old Weston, Cambridgeshire, S Swithun | 1 | c1699 | Oak | | 6.B | 4.3 |
| 6496 | Old Whittington, Derbyshire, S Bartholomew | 1 | | Timber | | | 6 |
| 6497 | Old Windsor, Berkshire, S Peter & S Andrew | 1 | 1890 | Oak | Mears & Stainbank | | |
| 6498 | Old Wolverton, Buckinghamshire, Holy Trinity | 1 | c1820 | Timber | | 6.B & 6.D | 6.X |
| 6499 | Oldberrow, Warwickshire, S Mary | 2 | 1875 | Timber | ? (unidentified) | | |
| 6500 | Oldberrow, Warwickshire, S Mary | 1 | 1875 | Timber | ? (unidentified) | | |