The Telegraph has it:
The industrial action was called by the Public & Commercial Services Union, which also represents civil servants, amid claims that it is not “Christian behaviour” to freeze workers’ pay.
Given that pay freeze, and denial of more than one request to amend it,
...the Church staff voted in favour of a strike, which took place on Friday afternoon. Union members demonstrated outside Church House in Westminster, where most lay staff are based, as well as at Lambeth Palace.
A spokesman for the Church of England said: “We're sorry PCS staff have voted (by 38 to 24, with 56 members not voting) for a half-day of industrial action.
“This means that 118 members of the union will be called out on strike on the afternoon of March 12; out of a total staff of 497.