A few thoughts about British Antique Telephones.
The British (1930's -1940's) era older 1/232 (pyramid phones) are rarer, but they were designed without an internal bell, which is fine as an antique, but they don't have that lovely bell sound (unless you buy a separate bell). However I love the shape. Separate bells range between £25 and £75 (depending upon type).
Because they have an internal bell and because of TV programs like "deal no deal" all the later black (1940's-1950's) 300 series telephones are very popular. Amongst the 300 series I prefer (and the most sought after is) the 312 (or 314 even rarer 3 button) with draw.
My personal favourite amongst all the working series telephones with an internal bell is the ivory 312 or 332.
In summary I believe all UK based bakelite telephones made before the late 60's are classic and collectable.
The main thing to avoid is ITI (India Telephone Industries) 300 style telephones, these are hard to spot until you get up close, but they are VERY VERY poorly constructed and I believe are nearly worthless.
I also recommend you have at least one modern (tone dialling) phone because when you are used to bush button phones the rotary phones appear to take ages to dial the number (particularly long distance calls).