All categories shown on Cat 9 of my photo licence show valid from 13-12-73 on Cat 10 box.I passed my test in 68 which was soon after my 17th birthday in late November 67.I would guess,then,that I passed my test on or around 13-12-68 which would be about correct.Apparently when the agency concerned with driving licences and tests(Ministry of Transport I believe) passed the responsibility to DVLA back in the 70's they did not pass on the driving test date records to the DVLA.It would appear that a good guess,,providing it is within a year,could not be disputed.