Have the Conservatives given up on winning back Rochester and Strood, the Kent seat won in November’s by-election by the Tory defector to Ukip, Mark Reckless? It appears so.

All the talk after the by-election victory was that Reckless would never hang on to the seat at the general election. But yesterday it appeared on a list – inadvertently leaked in a “cock-up” at Conservative party headquarters - of 101 seats now considered “non-target”.

(How the cock-up occurred is pretty arcane stuff: readers can learn more at ConservativeHome.com or at May2015.com.)

The definition of “non-target” is broad: it includes safe Tory-held seats where no special effort is needed; safe seats held by other parties that it would be pointless to chase when there’s clearly no national mood for a landslide election; and – this is where it gets strange – some marginal seats that most observers had assumed the Tories would be fighting tooth-and-nail.

Among the latter are Rochester and Strood and the Lincolnshire seat of Boston & Skegness. The appearance of the latter in the list of 101 is even more puzzling: the Tories are projected by May2015 to hold it comfortably, but Ladbrokes are backing it to go to Ukip. Whichever is true, you’d expect the Tories to be fighting to save it.

The Week’s poll-watcher Don Brind comments: “On the face of it, the idea that the Tories can't win an overall majority is a statement of the obvious. It's the view of virtually all poll-watchers and pundits.

“But the apparent confirmation that Team Cameron shares this gloomy view is likely to have a damaging effect on the morale of activists in the seats that have apparently been written off.

“There is still chatter in Tory circles that the opinion polls have got it all wrong, just as they did in 1992 when John Major confounded the pollsters and beat Neil Kinnock by eight points.

“But the pollsters have improved their techniques in the years since and we also have the innovation of Lord Ashcroft's constituency polls.

“Most poll averages show the Tories have been flatlining in the low-30s for more than a year. What this leak shows is that the Conservatives are in defensive formation, targeting seats they need to hold to be the biggest party rather than fighting to gain Labour seats.”