Thomas Kerr (below), who has served the Shettleston ward since 2017, made the move on Thursday – leaving the Tories with just one representative at Glasgow City Council.
Questioned on the defection by journalists at Holyrood, Findlay failed to stop speculation that there could be further Tory defections to Nigel Farage’s party.
The MSP argued that he could not control what other people choose to do.
“It’s obviously very disappointing to hear the news, to read about it this morning,” Findlay told reporters.
“My focus remains on holding this completely rotten SNP government to account. That’s my job, that’s what I’ve just done in respect of this shocking report with the RCN and the devastating state of the Scottish NHS.
“When I took control of this party I knew that we faced big challenges. I know people feel disillusioned and disconnected. It’s my job to confidently set out a Scottish Conservative range of measures, to persuade the people of Scotland, show the people of Scotland we’re on their side.”
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Asked if he expected further defections, Findlay said: “Any conversations I’ve had with colleagues ought to remain private and that’s something I’d respect.
“I can only control what’s in my gift to do so, I can’t anticipate what other people may or may not decide to do. It’s my job to make sure colleagues understand our direction of travel.”
Kerr’s defection came as a Holyrood poll from Survation put the Tories neck and neck, on 15 seats each.