Why did Shapps step down? A quick perusal of his Wikipedia entry gives a clue…
Shapps’s use of the names Michael Green, Corinne Stockheath and Sebastian Fox [as names he used to trade under] attracted controversy in 2012. He denied having used a pseudonym after entering parliament and, in 2014, threatened legal action against a constituent who had stated on Facebook that he had. In February 2015, he publicly said: “I don’t have a second job and have never had a second job while being an MP. End of story.”
However, in March 2015, Shapps admitted to having had a second job while being an MP, and practising business under a pseudonym.[26][27] In his admission, he stated that he had “over-firmly denied” having a second job.[28] In March 2015, Dean Archer, the constituent previously threatened with legal action by Shapps, threatened Shapps with legal action.
One would think that selection minions might wish to avoid another, embarrassing “does he tell porkies?” situation. The pseudonym issue is just one of the dodgy deals covered in the piece.