Someone cruising Lincoln MP Karl McCartney's Twitter favourites (as you do) this morning, discovered among tweets about positive goings-on in his constituency, an image of a woman tied to a bed wearing crotchless underwear.

It was a huge coup for rival Labour candidate Lucy Rigby, who tweeted a screen grab herself (but in her excitement forgot to censor it).

Mr McCartney appeared to eventually realise what was happening and started rampantly unfavouriting tweets, not just the graphic one but all of them, putting his favourite-count back down to zero.

The nation awaited the explanation (hacking? a prank by an intern?) and one was sort of give at lunchtime, when Karl wrote...

The MP seemed to imply that the favouriting was not done by him, which, if true, would surely make this one of the subtlest hacks on record.

Update: In a statement to The Independent, Mr McCartney said:

"It was brought to my attention earlier today by a number of people that a Twitter post from Lincoln Labour’s Prospective Parliamentary Candidate showed a pornographic tweet and around 50 other random tweets had been ‘favourited’ on my Twitter account from the past four years.

I have removed all ‘favourites’ from my account, I have reset my password and those who follow me regularly on Twitter will know that I have never been into the practice of favouriting tweets or images in my 6-7 years on Twitter and stick to posting or retweeting in the main (25k+) including at times images of interesting cars I see whilst out campaigning.