Who makes council policy?

I was hugely concerned last week to find out that the council was proposing to sell off land across from the Whitehall Theatre despite the fact that the council had a clear policy for the area
The work on the green space was meant to have been finished by now, yet very little has been done and the council seems to have forgotten its commitment.
I asked the chief executive why this has happened, and the response was that there has been a mix-up.
That’s not good enough – if this commitment has been forgotten that begs the question, what other policies aren’t being fulfilled?
I also think that there is a need for more transparency, meetings should only be held in private as a last resort.
I understand that due to business confidentiality some discussions need to be private, but there needs to be a balance to allow the public to stay informed.
There is a need for answers on this issue.  It may not be the biggest policy decision that the council ever faces but it is important to get to the bottom of who makes policy for the council and who has the right to overrule a democratic decision.