Hi

I have a feeling was the 1st year with all the fruit and flowers just out of a pot & planted , as it may just be sending out roots into the soil , typical of a newly planted tree just settling in to its new surroundings.

Gg

Snap

I usually give my trees a balanced fertiliser in spring,

If last year's flowering was exuberant, it might be taking a year off. Apples are known for this, termed biennial bearing. I've been having the same issue with my crab, of a different variety.
The strategy for overcoming it is to thin the fruit a couple of times during late spring and summer, so the tree doesn't get as exhausted. Not guaranteed to work though, but worth a shot next year.
The cold late spring we had this year will also have had an influence.

I think you'll find it was simply the very cold spring we had - if it flowered at all, they probably weren't pollinated, too cold for many insects to be about. I keep hearing people say what a lovely summer we had - we did, for about two months from the mid/end of June, but I recall clearly still running the heating at the beginning of June. March, April and most of May were really quite cold.