Members of the Public and Commercial Services (PCS) union began a 48-hour strike at HP today over a dispute over job security and pay.
The strike action affects work at the Department for Work and Pensions, the Ministry of Defence, and car manufacturer Vauxhall. Industrial action was also taking place at HP locations in Washington, near Newcastle, and Preston and Blackpool, the PCS said.
The dispute centres on pay freezes, as well as on the 3,400 EDS staff who have been made redundant since HP took over the company in 2008, and the 1,000 job losses planned for the first half of the year.
The strikes are taking place as non-IT workers in the civil service, also in the PCS union, stage a simultaneous high profile series of strikes affecting a range of services. Additionally, there are more than 20 rallies taking place.
Jim Hanson, national officer at PCS, was at the picket line at HP's office in Newcastle, where 25 people were demonstrating. "The car park is looking somewhat empty, so we've had a good day," he said.
"There was also a successful demonstration between 7.30am and 9.30am outside HP's headquarters in central London."
On Friday, HP insisted it was ready for the strikes. A spokesperson said: "In cooperation with our clients, we have put together a plan to mitigate the impact of the two-day action."
The dispute between PCS and HP has been going on since December 2009, when HP narrowly avoided a strike by union members by agreeing to sit down to talks at the eleventh hour.
After a one-day strike in January, Hanson said the union had had a couple of meetings with the mediation organisation Advisory, Conciliation and Arbitration Service (ACAS), but that HP "wasn't willing to move far enough."