You say tomayto and I say tomato

At the legal translation seminar in Munich I learnt that people at the European Patent Office don’t mind whether they or I write trade mark or trademark. (I had learnt that trade mark is British and trademark is American - perhaps I’m too much affected by the neue deutsche Getrenntschreibung).

I also gathered that everybody always says patent as in cat (I will call that ‘short’), rather than paytent (I will call that ‘long’ - does the IPKAT, as a cat, do that too?). This is worrying, as I always use the long pronunciation, but persons close to the patent office only say that for patent-leather shoes.

Longman’s Pronunciation Dictionary (first edition) says the standard BrE pronunciation is the long one, and the standard AmE pronunciation is the short one. It also says that when the short A is used in BrE it is mainly restricted to technical use (which is the use I’m concerned with), and when the long A is used in AmE it is only in the sense of ‘open, obvious’ (as in the latent / patent contrast).

Collins English Dictionary has an equally long note to the same effect. It does say that even in the technical sense, the long A pronunciation is commoner in BrE. So am I not alone?