But the solicitor would have seen the property sales particulars, and if they weren't provided with a copy they should have asked for one. This enables them to confirm exactly what is being sold, and that all the correct permissions are in place. It is also very likely that there would have been a report from the mortgage valuer, highlighting what is being sold, and asking the solicitor to ensure that all relevant permissions are in place. It is worth remembering that the solicitor handling the conveyancing not only acts for the purchaser, but also acts on behalf of the mortgage lender, assuming there is one in this particular case.
So, there is a far better chance of success by taking action against the solicitor who acted, rather than the EA.