Southwark Council's cabinet has voted to appoint the Labour council leader Peter John to the board of the Potters Fields Park Management Trust, replacing the Lib Dem Riverside ward councillor Nick Stanton.
The riverside park is held on a 30-year lease from the council by an independent trust whose board includes two council representatives. The council's current representatives are Riverside ward councillor Nick Stanton and chief executive Annie Shepperd.
On Tuesday the council's cabinet was asked to approve plans to appoint the council leader to the board of the management trust in place of Cllr Stanton.
The council now argues that the park's high profile means that a member of the borough's ruling Labour administration should have a vote on decisions affecting the park.
"This site is a strategic as well as local site," said Cllr Barrie Hargrove, cabinet member for environment.
"It has borough-wide significance and we feel that there is a deficit not having someone with a borough-wide strategic view on that body. That is the reason for change."
Cllr Hargrove emphasised the important role that Potters Fields Park will play in London's Olympic celebrations. It is one of three 'live sites' where Londoners and tourists will be able to watch the sporting events on big screens free of charge.
"[The live site status] has been given to us without the commensurate funding that we need to make sure everything runs smoothly and is cleared up afterwards," said Cllr Hargrove, who said this was "all the more reason" for the council to get more involved in the park.
Cllr Hargrove denied the suggestions raised by Lib Dem leader Anood Al-Samerai that Cllr John's desire to get involved with the running of the park was motivated by his frustration with the trust's rejection of plans for a 9/11 artwork created from steel salvaged from the World Trader Center in New York.
"That is not the case whatsoever," Cllr Hargrove told cabinet. "The 9/11 sculpture will be going to another London borough so it is not true at all that there is a connection."