Ny Easter Quiz Question: The Answer

I asked if anyone could guess which BTC/Tilling operator with a seventeen bus allocation at one of it's depots found on my 1967 PSV News Sheet on every single bus had at least one number nine in it's registration. The answer was Southern National at Seaton.

696 EDV 559D
980 KUO 993
986 KUO 999
1341 LTA 997
1342 LTA 998
1343 LTA 999
1344 MOD 971
1607 LTA 976
1762 RTT 981
1847 LTA 957
1851 LTA 994
1877 RTT 996
1913 UOD 496
1914 UOD 497
1915 UOD 498
1945 VDV 779
2613 911 AUO