It is 8pm and ahead of him is a 16-hour double shift cleaning in the Palace of Westminster. His duties include scrubbing the modern restaurant - where MPs and staff eat trendy grills - and scrubbing the vomit from the doorsteps along Whitehall. Later, he will scoop leaves and litter from the rooftops and drains of the Palace.
Today Mr Gebru, 42, and 140 of his colleagues will take part in a one-day strike aimed at shaming the authorities in the mother of Parliaments into coming to the negotiating table to increase their earnings above what their union calls "poverty pay".
He does not criticise the contractors who employ him and praises the MPs and staff he meets every day. But he says the cleaners are disappointed at pay rates in one of the most famous buildings in the world.
Housekeepers employed directly by the parliamentary authorities earn from £7.89 an hour, get 30 days leave on top of bank holidays, are entitled to sick pay and can join a pension scheme. Meanwhile, contract cleaners at the palace earn from £5.20 an hour, have 20 days' holiday - which includes bank holidays- and have no sick pay or pension, say union leaders. Mr Gebru, who worked as a building contractor in his native Eritrea before he fled to Britain to escape political violence 15 years ago, says: "When I started work here, I felt very very privileged. I could not imagine a person like me to come from where I was from and work in the Parliament.
"First of all, when people ask me where I work and I say I work in Parliament they are very excited. They think I get every right. I can't explain to them that this is how we are being treated and this is the pay we get. They cannot understand it."
When MPs return to their Westminster flats after the day's sitting, a small army of low-paid workers moves in to toil through the night, scrubbing the bars, restaurants, corridors and chambers in the ornate houses of Parliament and the offices that house members and their staff.
Mr Gebru earns £5.58 an hour for industrial cleaning in the kitchens, streets and roofs of the palace. But many of his colleagues take home as little as £5.20 an hour, just above the minimum wage of £5.05.
The Transport and General Workers' Union is locked in a dispute with the Commons authorities over their demand that their members' hourly pay be increased to £6.70 an hour.
The cleaners are employed by two contract firms, Mitie Cleaning and Emprise Services, but workers blame the Commons authorities for their low wages. Jack Dromey, the T&G deputy general secretary said: "Unelected, privileged civil servants are preventing hardworking cleaners form earning a living wage and receiving decent treatment."
A total of 165 MPs have signed a Commons motion condemning low pay among cleaners and calling on Parliament to "end this sorry state of affairs". So far, the House of Commons Commission, the committee of senior MPs responsible for running the Palace, has refused to offer more cash to cleaning firms to fund higher wages.
Meanwhile, Mr Gebru's shift continues. "It's physical, it's very, very demanding and you have to use chemicals. It's a very, very hard job, " he said.
At 5.30am his night-shift work is finished, and a supervisor comes to check all is spick and span. "The job needs to be immaculate," Mr Gebru says. "They are very very strict. Sometimes you think it's finished but a supervisor will give you another half-hour job to finish it."
Mr Gebru has one hour's break before his day shift starts with another of the two firms who hold the Westminster cleaning contracts. The contract staff have an office and a rest room tucked in between the red-brick Norman Shaw office buildings along the Thames that house many MPs' offices.
An hour later Mr Gebru is ready to start his second job of the day. First up is the grim task of scrubbing the Whitehall doorsteps of the parliamentary buildings across the street from the House of Commons proper. It can be revolting work. "The most difficult thing is if people have pissed here or there is vomit around. I have a broom and water and soap, a mop sometimes. If there is vomit I need a brush and disinfectant.
"I like to do the job as early as I can before many people are around. I try to do it as quickly as possible. I don't like to be seen doing it. It's a very, very ungood job. I'm embarrassed."
Three days a week, Mr Gebru works a double shift, to earn money to help keep his son while he continues his A-level studies. He works a 64-hour week, which means he earns around £370 a week, more if there is overtime.
He says his son's A-level course, and the chance that he will have a better chance in life, motivates him. "That is the thing that keeps me going. I don't want to repeat the pattern."
* Contract cleaners at the House of Commons earn from £5.20 an hour, receive no sick pay and have no pension. They have minimum holidays of 20 days a year including bank holidays.
* Housekeepers, employed directly by the parliamentary authorities, earn from £7. 89 an hour, have 30 days' holiday a year, access to a pension scheme and a year's sick pay.
* Cleaners in the City earn between £6 and £6.70 an hour.
* The national minimum wage is £5.05 an hour.
* Last year average hourly earnings in Britain were £10.56 for full-time staff.
* MPs earn £59,095 a year. They have a generous pension scheme, paid for by contributions of 6 or 10 per cent of their salary. MPs with constituencies outside London can also claim £20,000 a year to cover the cost of running a second home, as well as staff and office expenses. In the 2004-05 session, MPs sat at Westminster for 151 days.
* Cabinet ministers earn a total of £133,997 a year.
* Tony Blair earns a total of £183,932 a year.
* A minister of state earns a total of £97,949 a year.
* Peter Grant Peterkin, the serjeant-at-arms, earns about £100,000 a year.Reuse content