Cause and effect
The Sunday Times is confusing cause and effect in its article (http://www.timesonline.co.uk/tol/news/politics/article6788780.ece) saying that "more than 50 prospective candidates chosen by the main parties are already working as lobbyists and public relations executives".
It isn't "that parties were recruiting lobbyists" as the article says, it's that there aren't many other careers that are compatible with the pressures of running for parliament.
In my case I had to resign as a local government officer when I was selected to fight un-winnable Aldershot in 2001. I made myself unemployed by becoming a PPC because of the Widdecombe rules restricting political activity by public servants and was lucky that my current employer, a public affairs company, stepped in.
Not many "non-political" employers would accept someone saying they needed a month's annual leave all in one block, couldn't predict when this would be, and would have to down tools at the minute the PM's car left for Buckingham Palace in order to leaflet returning commuters. Nor would many conventional employers tolerate months of early starts and 4.30pm finishes in order to get out to the constituency in time for canvassing or party meetings.
The publicity can scare "non-political" employers too - I know one PPC in a winnable seat who was laid off by a major corporation because they did not want their company name linked in the press to a political party.
So given the need for parliamentary candidates to feed their families and pay the mortgage, unless they are self-employed (e.g. barristers) or already working in quasi-political jobs (unions, think-tanks etc) yes a lot of them end up working in public affairs jobs between selection and election - it doesn't actually tell you that much about the composition of parliament.