The Party Wall etc. Act allows for one surveyor to represent both parties to a dispute. (i.e. the Building Owner and the Adjoining Owner). The party wall surveyor should be fair and honest at all times to properly represent both their interests.
This arrangement can work well with straight forward matters and when the neighbours get on well — and especially when the matter is non contentious. If a party wall surveyor sees issues that are likely to be problematic or contentious, it is sometimes best to decline an agreed surveyor role.
As the Act enables and allows the parties to the dispute to agree that one surveyor will represent them both this option should be considered favourably as this can be a cost effective and usually a quicker way of dealing with straight forward and non-contentious matters. However, both parties have to agree and equally the surveyor must be comfortable that the matter allows for such with no potential for a conflict of interest.
In order to identify if a single agreed surveyor role could be contemplated it is best for a full set of drawings to be provided for review by the surveyor. Working drawings with any associated engineering details rather than planning drawings.
It is very important for the surveyor to feel comfortable with the proposed arrangement and this often warrants initial communication with both parties to get a feel for any issues and concerns.