If you fly BA from North America on a 777 or 747 you will get the Club World seat in J. Personally I find the seat quite narrow too but it is excellent for sleeping on. If you can get upper deck seats on a 747 and go for a Window then you have a little more wriggle room.

The A318s from JFK to LCY have Club World London City seats which are different to the normal Club World Seats and I believe there may be a few 767s flying from select North American cities that have the old Club World product on them (still lie flat, but different design).