A Liberal Democrat councillor expelled from the party for his opposition to the Beddington incinerator has joined the Green Party.

Cllr Nick Mattey will continue to sit as an independent councillor for the remaining two years of his term before standing for re-election as a Green in 2018.

RELATED: Lib Dem councillor expelled for publicly opposing Sutton Council's incinerator plan

He faced a disciplinary hearing at Lib Dem headquarters in January, when a panel ruled he had breached party rules for opposing Sutton Council's approval of Viridor's controversial incinerator.

The panel also found he had actively campaigned against his own party in public elections.

Cllr Mattey's subsequent appeal was rejected by the Lib Dems and he has since sat as an independent.

RELATED: Lib Dem who opposed Sutton Council's incinerator plan suspended

He announced his decision to join the Green Party, which has vocally campaigned against the incinerator, on Monday, and described the move as the "natural next step"

He said: “I resisted my expulsion from the Lib Dems because I wanted to carry on fighting this battle from within, but joining the Greens has been a natural next step, not least because of their long support locally for the campaign against the incinerator.

“I will sit on the council as an independent because it would be unfair to the voters who elected me to change party mid-term.

“But I will be seeking re-election as a Green in 2018 and I hope I won’t be the party’s only successful candidate in Sutton.

“The ruling party has behaved disgracefully throughout this episode and voters won’t forgive them easily.”

Cllr Mattey was suspended by the Lib Dems in April last year after making public a 1,500-word letter in which he backed the Stop the Incinerator, led by Green Party member Shasha Khan, who took the council's approval of the scheme to a judicial review.

In the letter Cllr Mattey criticised his fellow Lib Dem councillors for standing "shoulder to shoulder" with Viridor and urged them to “forget behaving as a group and to begin to think independently and critically”.

RELATED: Green mayoral candidate Sian Berry pledges to stop Viridor incinerator months after work begins

Sian Berry, Green candidate for Mayor of London, this week said Cllr Mattey's opposition of the incinerator as "to his immense credit."

She has pledged to push for an inquiry into the scheme, which she described as "by far the worst form of waste management," if she is elected.

Ms Berry: “Nick, who has been an outspoken critic of a scheme that has been imposed on the people of Sutton and Croydon in the face of huge local opposition.

“It’s to his immense credit that he put the health of local residents above blind loyalty to his party."