A confusing Contract Law question.

Is the solicitor for a company who signs a contract of behalf of that company a third party to the contract or, one of the parties entering the contract?

The question is regarding Dave who is a pool builder and is entering a contract to build a pool for a hotel.


Here is the scenario.
"Heather, the solicitor for OCV Ltd read clause 5 of a contract which stated:

It is the responsibility of the owner to ensure that the proposed site is suitable for the construction of the pool and to obtain any consent required under law.

Upon reading, she stated that the contract would need to be delayed to allow for written approval from the local council. Dave the pool builder immediately replied that he would take the responsibility of checking with the local council and let Heather know if there was a problem. Heather then signed the contract on behalf of OCV Ltd.

When Dave begun construction, he dug into a water drain and it was discovered he had never checked with the council as to the suitability of the site. He walked off the job and refused to return the site to its original condition."

So, I have a few questions:
1. Is Dave liable for the damages?
2. Is Dave's oral statement that he would check with the council sufficient to cancel clause 5?
3. Would promissory estoppel apply where Heather is relying on Dave's statement?

In answering this, Clause 11 states that "This document constitutes the entire agreement between the parties and no representations, conditions or warranties are of any legal effect."

Thanks