Cryptic crossword No 78

This is my first grid and my first attempt to clue this contained many mistakes (only 7 clues survive relatively unscathed). I’m grateful for the patient and detailed feedback that I received on this in draft, which alerted me to the types of mistake I was making. It will still be rough around the edges, but an improvement. This is themed, but not always obviously so and I’ve added some additional notes which will be of interest to those who celebrate this anniversary! Feedback welcome. Thanks

Enjoyable crossword and some nice clues. As you yourself admit, it's a bit patchier than the last one of yours I tried, but that's understandable if this was actually your first attempt. Some clues were very easy; others a bit over-convoluted. Maybe you shouldn't have tried a difficult theme for your first attempt! Having said all that, there's some really good stuff - I liked 1a, 6d and 19d particularly. Think there might be a spelling mistake in the answer to 8d

A correction has been made to 8 down.

Thanks Guava. Favourite clues were 12a, 15a, 3d, 5d and 7d. SPOILERS in reply...