I Don't Think It's A Breitling Top Time, for one simple reason: Tri-Compax Top Times have very small sub-dials, and in fact, the only thing I don't like about those. Otherwise, at 38mm, I consider it the perfect vintage chronograph. Definitely the right size. The one Jimmy is wearing in the picture seems to be a chronograph with larger sub-dials.
Please have a look:

In my opinion, had that been a Top Time, the sub-dials would look quite a bit smaller.
Unless I can see a better picture or a close-up, I refuse to believe it is a Top Time.

What do you think?

Regards

Darwin

PS: He was my dad's favorite F1 driver... he always referred to him as "The Jimmy".