Many happy returns of the day before yesterday, Jack !
Just out of interest, have you got 78 years' worth of records to go with your memories. It would be fascinating to see things like your 'first small tortoiseshell of the season' dates going back that far.
Foolishly - and now with regrets - I never kept diaries so can't look at changes of dates, etc.
But memory does offer a few clues. I lived in the relatively warm East Anglia. Back in the late 1940s / early 1950s, it was unusual to see Orange Tips before early May. One year soon (if not already) there will be a February sighting.
So this old man says to any youngsters who might be reading this: DO KEEP DIARIES. You might find them boring and a bit of chore now but they won't be early in the 22nd century when you can look back at them.