Stanley started making the #78 in 1884 and continued to do so well into the 1980s. For at least 100 years the #78 was one of Stanley's "bread and butter" planes. They literally sold millions of them. When Stanley started to drop various hand plane patterns from its product line in the 1940s, the #78 survived and was eventually manufactured in England. Unfortunately, from a collector's standpoint, just about every Stanley plane made in England doesn't seem to carry the same value as its earlier produced, USA made siblings. Unlike Gibsontool, I haven't collected more than 400 planes..... yet, but I've still got more than my share. Based on my plane collecting experience, only mint condition, still new in the original box, made in the USA, earlier versions (pre-1950) of the #78 could possibly command $125. I really don't think that a comparable English made #78, still in it's original box, would even exceed $50. From what I've seen, English made Stanley planes aren't that collectible.
Wow Gibsontool, a collection of 400 planes is impressive! I wouldn't mind seeing some of your "gems." Post a few pictures!!
Jim C.