Johnny Mercer was never a politician willing to toe the line for advancement

The ex-defence minister says he got into parliament to improve care for mentally ill veterans, and will continue to fight for their protection from the backbenches, writes Andrew Woodcock

To his admirers, Mercer was fighting in defiance of Westminster careerism (Chris McAndrew / UK Parliament (Attribution 3.0 Unported (CC BY 3.0)))

The spectacular resignation of Johnny Mercer, which briefly diverted Westminster from contemplating the contents of Boris Johnson’s mobile phone earlier this week, puts him in a small category of politicians whose devotion to a cause has ended their rise up the greasy pole of ministerial rank.

It’s by no means unheard of for ministers to resign on a point of principle or disagreement with a particular government policy.

But few MPs identify themselves so clearly with a single issue that stands above party loyalties or personal advancement.