the house was built in the 1920 s so not built with insulation or sound proofing in mind I have heard of putting new layers of plaster or acouistic mats on all party walls
there is a product from kingspan (dont know the details) that is used to sound proof walls and floors . its not cheap from what I can gather but if your problem is serious then its worth considering...
hiyahave been looking for the same stuff myself. and i came across a product from moy insulation which i have just ordered from chadwicksIts called calibel. basically its sound proff insulation attached to plasterboard. I have not got it installed yet so at this point i can't comment on if it works.[broken link removed] have the same problem as yourself - we can hear the tv, phone, talking from our neighhours - we also in an old 1930 house
Put up some 2x2 lats and pack it with rockwoll. Then put fresh plaster board over it and give it a skim. It's also a good opportunity to hide pipes and wires etc so plan it out.