Labour's winning candidate in Stroud says he is exhilarated and surprised.
David Drew beat Conservative Neil Carmichael by 681 votes. There was a 9.3% swing, with UKIP and the Green Party losing their share of the vote.
Mr Drew said he was exhilarated "in the sense that nobody expected this including me".
Mr Drew added: "I've lost twice in the last seven years, I didn't expect to come back. It was a shock to come back.
"But with snap elections sometime people who call them regret that and others gain from that, I have gained."
Conservative Geoffrey Clifton-Brown, who was elected to the Cotswolds constituency, said the Tories needed to have an inquiry and lessons needed to be learned.
"It started with the social care tax and once you've made one big mistake than that opens the floodgates to all sorts of other issues."
Asked if Theresa May should go, he said "we will have to see what happens in the next few weeks".
"I hope not because that will bring more instability into the country," he added.