You've come to the right place to ask the question, but I doubt anyone's going to give anything more than the most cursory opinion without detailed pictures. The pictures should be of the barrel flats and watertable, and some overall pictures of the gun, receiver, and serial numbers (if any).
I'm far from an expert on Ideals, but I've never heard of one with external hammers. That doesn't mean they don't exist, just that I've never heard of one. Along the same lines, it's not impossible that an Ideal would have British proof marks, just uncommon.
