I got fired 5 years ago from BB

Guys - I got fired five years ago from a BB after spending a few years there for compliance reasons. Was thinking of writing a book on ib without prior approval (emailed a publisher) and compliance somehow found my emails a year later. It was pretty stupid but despite that I had still gotten interviews / offer from a eb and Bb (which I had turned down) . I left finance, joined a decently successfully small tech co in a leadership role and then went to bschool where I also worked in PE for a year to two. When walking folks through my resume I just say that I wanted to diversify beyond finance and so left Bb. Never saw the merit of disclosing something five years ago esp when I’ve done so much since then. Should say though that this was not the case though when I was interviewing five years ago as I’d proactively tell firms that I was fired.

Anyway Now I’ve been extended an offer and I am wondering if I need to disclose my prior termination / will they ask me...because I am Sure if my bank’s Hr is called, they’ll say I was terminated for breach of bank’s policies

This should not be on my fca record though as I hadn’t taken the fca (eq of series) exam yet