Hi
The people who sold you your house were not obliged to specifically tell you who was living next door to them.
However, If they had any 'problems' with the neighbours, such as... complaining about music/noise/anti-social behaviour, then yes, they had a legal duty to disclose such problems on the Sellers Property Information Form (SPIF). This form is part of the conveyance procedure, and is a legally binding document.
Technically you can sue the previous owners, if you have proof that they lied or misrepresented the situation with the neighbouring house. BUT... this is a very costly avenue to go down.
I am not too sure on the solicitors responsibility. I would have thought that it may have shown up on the land search???
I am sure some of the legal bods on here will be along soon to answer this.
JJ