Buying a house that a developer took in part-exchange and therefore has no personal knowledge of

Tiglet2

The conveyancer acts in the transfer of the property from A to B.  They investigate the title, rights of way and any restrictions relating to the property, together with raising enquiries about any legal issues that might crop up.  They do not investigate non-legal issues, such as the answers provided on the Fixtures & Fittings and Property Info Form.  Obviously if there are certificates/warranties and paperwork covering appliances and/or building regulations etc, then I assume you will be provided with these in the paperwork that the seller has.  The conveyancer can't give you much advice regarding the forms because they do not visit the property.

Your due diligence is needed to investigate anything which you are worried about, so a survey is a good idea and perhaps taking along a builder when you next view.  I'm assuming you are also obtaining searches, i.e. Local, Environmental, Water & Drainage.  You could also check the council planning website to see if there are any planning decisions/applications nearby that would affect the property.   When you next view, turn on taps, lights and the boiler, open doors and windows to check they open and shut properly, generally have a good poke around to make sure there are no obvious signs of damp, subsidence etc.  

As others have said, probate properties are usually sold by an executor who also may not know much about the property.  Not unusual.

One thing I will add, is where people have disputed something that the previous owner did or did not disclose in the protocol forms, they would have to instruct a litigation solicitor to deal with it, as conveyancing solicitors won't usually act as litigators as they have no expertise in this.  The cost of the legal fees is often much higher than the compensation claimed for.  The protocol forms form part of the 'contract', but it is not that easy or straightforward to enforce.  As someone else said, the boiler could be in working order on the day before completion, but breaks down the day after.