This quote is taken from the article linked above (my underlining). Long time since I did economics, but isn't somebody who sits on the board usually a director? Can't see what is so surprising/sinister about councils who are shareholders of the airport company having seats on the board?
Despite owning fewer shares, Darlington Borough Council leader Bill Dixon insisted that the council’s influence over the airport will not be compromised.
He said: “It was in our agreement with Peel from the start that over time the local authorities’ share options would decrease as they put more capital in. I will continue to sit on the board and, in real terms, our influence will not be affected. Even combined – the local authorities were minority shareholders, so we couldn’t really veto anything done by Peel. I am concerned for the future of the airport, but not in relation to this. It doesn’t matter who owns what, so long as it is running.”