who knows when the timing covers altered? its about the same as when did the word VINCENT appear on the cover? there was a period when they dropped the HRD and before the VINCENT batch came in when plain covers were used. very useful when we were sorting the racing comet out for VMCC racing when the VOC stopped their race meetings. (yes newcomers once we could fill a race paddock with Vincents, now we mostly fill museums) we only got in the pre 48 by the skin of our teeth because the first comet was shown on the autumn 1948 earls court show stand and someone (bless them) had taken a picture with a caption, so to have a cover with VINCENT on or HRD would have added to the controversy so that's one plain cover that started out VINCENT