Old Ordnance Survey maps for Kent are available to purchase from Alan Godfrey Maps.
A full list of Kent maps with their original date are shown below:
13.06 Sheerness 1931
23.10 Whitstable (North) 1906
23.13 Whitstable (West) 1905
23.14 Whitstable (East) 1906
25.04 Margate (North) 1896
25.08 Margate (South) 1896
33.01 Sittingbourne 1897
34.09 Faversham (SW) & Ospringe 1906
34.10 Faversham (SE) 1906
38.01 Ramsgate 1905
40.01 Sevenoaks (N) 1907
40.05 Sevenoaks (S) 1907
42.03 Maidstone (North) 1868
42.07 Maidstone (South) 1868
46.03 Canterbury 1906
50.12 Tonbridge 1895
58.04 Deal 1871
60.11 Tunbridge Wells (NW) 1907
60.12 Tunbridge Wells (NE) 1907
60.15 Tunbridge Wells (SW) 1907
60.16 Tunbridge Wells (SE) 1907
65.05 Ashford 1896
65.09 Ashford (South) 1896
68.14 Dover (South) 1897
75.10 Folkestone 1906
The maps generally cost £3.50 each and can be purchased online from the Alan Godfrey Maps website.