Government staff working directly for the Prime Minister were among 125,000 civil servants that joined industrial action today.
The Prime Minster's official spokesman confirmed that "a handful" of Downing Street staff were among those on strike, but did not specify how many.
It was reported that even the press officer leading the Cabinet Office's media response to the strikes took part in industrial action today, though the Prime Minister's spokesperson would not confirm if this was the case.
As the Prime Minister described the strike action as "damp squib" in the House of Commons, union members - among them diplomats, senior managers and strategists from a number of Whitehall departments - rallied outside Parliament.
The Treasury and the Cabinet Office were picketed this morning by members of the FDA Union. Several thousand attended a rally at the Embankment in the afternoon, where union bosses pledged to return to strike action in the new year if a better deal was not offered by the Government.
Parliament's own security, maintenance and catering staff also took the picket lines in Westminster today.
One of those on strike, who asked not to be named, said he has painted the walls inside Parliament for 36 years and was now on strike for the first time. He has seen seven Prime Ministers rise and fall and has given the Chamber a lick of paint before every state opening of Parliament in his long career.
"This won't affect me because I'll retire soon on the old deal, which isn't much in itself," he said. "But I am more concerned for the future wellbeing of my colleagues than I have been in 36 years of working here."
Ambrose Richardson, an economist at Her Majesty's Revenue & Customs, who joined the walk-out yesterday, also said that he had never been on strike before.
"This is about both pay and pensions," he said. "The Government did not negotiate over capping the pay of public sector workers, nor did they negotiate on our pension contributions."