The VBAX code is the 1979 'National' coding applied to the BMX_ class. The class was recoded between 1978 and 1981.
The numbers were:
1, 2, 4 - 6, 10, 12, 13, 16, 17 20, 21, 23, 24, 27, 31 - 33, 36 - 39, 41, 46, 47, 50 - 52, 54 - 56 59, 62, 64, 65, 68, 70, 77, 78 98, 100
One BLX_ van was mislettered to VBAX during the recoding. BLX 113 was lettered VBAX 113 instead of VBBX 113 for several months in 1979.