The first major opinion poll carried out in Rochester and Strood since Mark Reckless announced he was joining UKIP has given him a nine-point lead over the Conservatives.

Mr Reckless announced last week that he was becoming the second Tory MP in a matter of weeks to switch to Nigel Farage's party.

He said at the time he was taking a gamble and would not necessarily win the subsequent by-election.

But a poll carried out by Survation on behalf of the Mail on Sunday gave him 40% of the vote, ahead of the Conservatives (31%), Labour (25%) Lib Dem (2%) and other (2%).

Mr Reckless won Rochester and Strood in 2010 with 9,953 votes to spare; however no UKIP candidate stood in that election.

The poll findings come as both parties began their campaigns in earnest, flooding the constituency with activists to drum up support.

Craig Mackinlay, the Medway councillor who is taking on Nigel Farage in Thanet South, said the poll was not a surprise at this stage of the campaign and predicted the party's ratings would recover once the issues were debated.

Asked if he thought the poll would come as a shock to the party, he said: "No, I do not think so, not at this stage of the campaign.

"We have not got a candidate in place while Mark Reckless has had the benefit of planning this."

"We have the issues - other than the EU and immigration, UKIP doesn't have any."

That was echoed by Andrew Mackness, the chairman of the Rochester and Strood Conservative association. "The feedback we are getting is very positive and solidly behind us and whoever the candidate will be."

Although UKIP will welcome the poll result, it is actually far closer than the Essex seaside resort of Clacton - where Douglas Carswell became the first Tory MP to switch sides.

Polls there have put Ukip on 56% of the vote, 31 points ahead of the Tories.

Mr Reckless said: "We are finding extraordinary levels of support on the doorstep.

"I am particularly pleased that a lot of that is coming from people who previously voted Conservative but also large numbers of Labour voters.

"There is also a big number of people who have become so disillusioned with politics that they have not voted for a generation."

"I was expecting a positive response. UKIP supporters who have come down to help have been surprised at the levels of support we are getting."

Read our political editor Paul Francis's take on the Rochester and Strood by-election by clicking here.