A secret email that could “make a mockery” of Kingston Council’s scrutiny process is being withheld.

The council has twice refused to release an email sent by the Liberal Democrat head of office to a councillor about who could sit on a panel discussing the closure of the borough’s last residential care home.

The decision to close Murray House was made in June, and was then taken to a Scrutiny Committee in July to be looked at again.

Deputy leader of the council Malcolm Self assured the committee that the Liberal Democrat administration councillors had not been “whipped”, which campaigners say would undermine the whole process.

But according to the councillor who received the email, it makes a link between who could sit on the panel and the “group line” – effectively ensuring a decision the administration wanted.

New Malden campaigner Lynne Finnerty submitted a Freedom of Information request asking for the council to release any email from an officer to councillors about who would be allowed to sit on the panel.

The council delayed its response and eventually refused to release the email (saying it was held by the party, not the council, and is therefore exempt), and Ms Finnerty submitted a complaint to the Information Commissioners Office,.

However an ICO spokesman said he could not confirm whether the Commission is investigating individual cases.

After an internal review, the council once again refused to release the email, and claimed the FOI request was “vexatious” in that it targets a specific officer.

Ms Finnerty said: “It seems to prove to me that the council is trying to hide something.

“I really don’t know how long it’s going to take, but if it’s released, and it shows that an email does exist, it proves that Cllr Self lied.

“I don’t want a witch hunt, but I don’t know why they are trying to evade this. I just want to make sure that in future the rules for the Scrutiny Committee are tighter.

“It’s not going to change the decision, but it would make a mockery of the process.”

This week, Councillor Sharron Falchikov-Sumner, who resigned in the wake of the Murray House decision, published a blog post confirming the email exists, but she is legally unable to say what it contains.

She wrote: “Local people need to be confident in the decisions their elected representatives make – whether they agree with them or not.

“It is clear that many committee decisions require a group line to allow the administration to get the job done and their manifesto commitments carried out.

“But scrutiny is different. Scrutiny is residents’ last opportunity to have their views heard and they need to know they will be listened to – and where decisions have been poorly executed, they can be looked at again.

“So councillors have a duty to weigh up the evidence in front of them with open minds.

“It is why Scrutiny Committees are legally supposed to be non-partisan and not pre-determined.

“It was clear the email undermined this important principle.”

Councillor Liz Green, leader of Kingston Council, said: “In bringing back Scrutiny to [the council], after the Conservatives abolished it, I wanted to make sure our decision making is efficient, transparent and accountable.”

She outlined the financial reasons for closing Murray House, and insisted “none of the Liberal Democrat councillors on the Scrutiny Committee were whipped”.

Cllr Green added: “Having heard all the evidence, all councillors on the Scrutiny Panel voted to uphold the decision.

“The interests of the elderly residents, particularly securing alternative residential care homes, were of paramount importance during the process.”