H licence question

[Ron Pier]

Andrew it's all a bit of a mystery! But unless your licence has the 'H' on it. You are not licensed for track laying.
Here is mine which I don't fully understand.
I passed my driving test around 1965. And yet it states 1975? This could be after a 10 year renewal and issue of a new licence.
I passed my motorcycle test in 1995, which is correct on the licence.
But I passed my H test about 7-8 years ago and yet it states 1975???

There must be an explanation, but I'm not about to even query it. Ron