select entry in Code column to view full DE allocations in that range
| Code | DEF | Operator | Use | Notes |
| 1900 | Workington | |||
| 1901 | Geographic - unassigned | |||
| 1902 | Wolverhampton | |||
| 1903 | Worthing | |||
| 1904 | York | |||
| 1905 | Worcester | |||
| 1906, 1907 | Geographic - unassigned | |||
| 1908 | Milton Keynes | |||
| 1909 | Worksop | |||
| 1910, 1911 | Tyneside/Durham/Sunderland National dialling | ELNS | ||
| 1912 | Tyneside | ELNS | ||
| 1913 | Durham | ELNS | ||
| 1914 | Tyneside | ELNS | ||
| 1915 | Sunderland | ELNS | ||
| 1916 | Tyneside | ELNS | ||
| 1917, 1918, 1919 | Tyneside/Durham/Sunderland expansion | ELNS | ||
| 1920 | Ware | |||
| 1921 | Geographic - unassigned | |||
| 1922 | Walsall | |||
| 1923 | Watford | |||
| 1924 | Wakefield | |||
| 1925 | Warrington | |||
| 1926 | Warwick | |||
| 1927 | Geographic - unassigned | |||
| 1928 | Runcorn | |||
| 1929 | Wareham | |||
| 1930 | Geographic - unassigned | |||
| 1931 | Shap | |||
| 1932 | Weybridge | |||
| 1933 | Wellingborough | |||
| 1934 | Weston-Super-Mare | |||
| 1935 | Yeovil | |||
| 1936 | Geographic - unassigned | |||
| 1937 | Wetherby | |||
| 1938 | Welshpool | |||
| 1939 | Wem | |||
| 1940, 1941 | Geographic - unassigned | |||
| 1942 | Wigan | |||
| 1943 | Guiseley | |||
| 1944 | West Heslerton | |||
| 1945 | Wisbech | |||
| 1946 | 0&1 | Whitehaven National Dialling | 4 Digit Code Area | |
| 1946 | 2-6 | Whitehaven | 4 Digit Code Area | |
| 1946 | 7 | Gosforth (Mixed) | 5 Digit Code Area | |
| 1946 | 8&9 | Whitehaven | 4 Digit Code Area | |
| 1947 | Whitby | |||
| 1948 | Whitchurch | |||
| 1949 | Whatton | |||
| 1950 | Sandwick | |||
| 1951 | Colonsay | |||
| 1952 | Telford | |||
| 1953 | Wymondham | |||
| 1954 | Madingley | |||
| 1955 | Wick | |||
| 1956 | Geographic - unassigned | |||
| 1957 | Mid Yell | |||
| 1958 | Geographic - unassigned | |||
| 1959 | Westerham | |||
| 1960 | Geographic - unassigned (formerly Ballyclare) | |||
| 1961 | Geographic - unassigned | |||
| 1962 | Winchester | |||
| 1963 | Wincanton | |||
| 1964 | 0&1 | Hornsea/Patrington National Dialling | ELNS | |
| 1964 | 2 | Hornsea | ELNS | |
| 1964 | 3&4 | Patrington | ELNS | |
| 1964 | 5 | Hornsea | ELNS | |
| 1964 | 6&7 | Patrington | ELNS | |
| 1964 | 8&9 | Hornsea | ELNS | |
| 1965, 1966 | Geographic - unassigned | |||
| 1967 | Strontian | |||
| 1968 | Penicuik | |||
| 1969 | Leyburn | |||
| 1970 | Aberystwyth | |||
| 1971 | Scourie | |||
| 1972 | Glenborrodale | |||
| 1973 | Geographic - unassigned | |||
| 1974 | Llanon | |||
| 1975 | 0&1 | Alford/Strathdon National Dialling | ELNS | |
| 1975 | 2 | Alford (Aberdeen) | ELNS | |
| 1975 | 3 | Strathdon | ELNS | |
| 1975 | 4&5 | Alford (Aberdeen) | ELNS | |
| 1975 | 6-8 | Strathdon | ELNS | |
| 1975 | 9 | Alford (Aberdeen) | ELNS | |
| 1976 | Geographic - unassigned | |||
| 1977 | Pontefract | |||
| 1978 | Wrexham | |||
| 1979 | Geographic - unassigned | |||
| 1980 | Amesbury | |||
| 1981 | Wormbridge | |||
| 1982 | Builth Wells | |||
| 1983 | Isle of Wight | |||
| 1984 | Watchet | |||
| 1985 | Warminster | |||
| 1986 | Bungay | |||
| 1987 | Geographic - unassigned | |||
| 1988 | Wigtown | |||
| 1989 | Ross-on-Wye | |||
| 1990, 1991 | Geographic - unassigned | |||
| 1992 | Lea Valley | |||
| 1993 | Witney | |||
| 1994 | St Clears | |||
| 1995 | Garstang | |||
| 1996 | Geographic - unassigned | |||
| 1997 | Strathpeffer | |||
| 1998, 1999 | Geographic - unassigned |