Theresa May hoping for a landslide victory in snap British election but is that really likely?

While there will be caution about placing too much weight on the polls after the experience of the 2015 election, when they failed to forecast a Tory victory, the confidence in the Conservative ranks is palpable.

With the main opposition in disarray, there were Tory MPs talking openly about the prospect of "slaughtering" Labour at the polls.

Theresa May will go to the country promising that they are the only party which can be trusted to deliver on last year’s referendum vote for Brexit and negotiate the best deal for Britain.

The British Prime Minister will be looking to strengthen her position in the Commons, where she has a slender working majority of just 17, and stamp her authority on her own party .

Currently she is vulnerable to rebellions by relatively small numbers of Conservative backbenchers if they can combine with the opposition parties.

She will also be hoping that gaining her own mandate will enable her to pursue her vision of Brexit, and to face down hardliners in her own ranks who may be unhappy at some of the trade-offs that emerge in the negotiations.

However the party could face a more difficult task than is thought in "winning really big", a prominent election expert has warned.

Professor John Curtice suggested the Prime Minister would need a lead of greater than 10 points to get the large government majority she wants to make her task of delivering a successful Brexit easier.

Mrs May, who has a fragile working majority of just 17 in the Commons, said she wants "unity" at Westminster as talks on Brexit begin in earnest with the European Union.

The Tories currently lead Labour by an average of 17 points in opinion polls, which Prof Curtice acknowledged would be enough to secure a landslide on June 8.

But he said that with the SNP expected to win the majority of Scottish seats, putting the nation "out of the game" in terms of forming a government, it has become a lot harder to win a large Commons majority.

Speaking on BBC Radio 4’s World at One, he said: "An awful lot of Labour seats are astonishingly safe and therefore even with a 15-point lead, well yes I think Theresa May at that point will get past the 100 majority mark.

"But let’s just imagine that the lead falls back to seven, eight, nine, 10 points - well, back in 2015, a seven-point lead over Labour was only enough to get a majority of 12 and that was only achieved by winning a lot of seats off the Liberal Democrats.

"So the truth is given the way that Scotland is now out of the game, given how few marginal seats there are in the country, winning really big has got a lot more difficult and that in a sense is the objective that Theresa May has now given herself."

But Prof Curtice acknowledged that Labour’s dismal performance in opinion polls had almost certainly been at least part of Mrs May’s motivation in calling an early vote.

"Labour will enter this election in an even worse position than it entered the 1983 general election when it ended up with 28% of the vote and I think, in truth, no opposition has gone into a general election in a weaker position than Labour will fight this election," he said.

"So to that extent at least this is a great temptation for Theresa May."