We're not used to seeing this model in gold Apo, it looks very much like a 110.255, which is gold-plated. Albeit a very pristine 110.255 and very nice indeed!

Could you let us know the model reference and serial number (they are usually on the caseback of a 110.255, but may also be between the lugs)? A photograph showing the caseback (ideally inside and out but I understand if you don't want to open the watch) and another showing the side of the watch with the pushers would help a lot too.

You might just have uncovered a new model that we were previously unaware of!