Voters in the South West constituency that includes Richmond and Kingston have kept their Conservative representative on London Assembly by re-electing Tony Arbour.
Cllr Arbour said he was not surprised to keep hold of his seat of 16 years but expressed disappointment that Zac Goldsmith appears unlikely to become London Mayor.
He said: "I would say the South West has always been firmly Conservative.
"Martin Whelton was leading at first because they counted Hounslow first. I wasn't worried.
"I want to thank the hudnreds of people who have worked terribly hard for me and Zac Goldsmith over this campaign."
Second place Mr Whelton, who serves as cabinet member for education on Merton Council, admitted he was disappointed but said he was incredibly proud of Labour's performance across London today.
Martin Whelton
He said: "It's been an extremely positive campaign fought over the main issues affecting Londoners today.
"Sadly I fell short, but I look forward to Sadiq Khan being Mayor of London, and to working with Leonie Cooper as she becomes Assembly member for Merton and Wandsworth."
He added: "It's been a good day. It's not been the best day of my life, but I'm so proud of everyone for all the work they have done over the last few months for me."
Follow all our live coverage of the London Mayor and Assembly election results day here
The overall results were:
Tony Arbour (Conservative) - 84,381
Martin Whelton (Labour) - 62,937
Rosina Robson (Liberal Democrat) - 30, 654
Andree Frieze (Green) - 19,745
Alan Craig (Ukip) - 14,983
Adam Buick (Socialist) - 1,065
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