I worked in Parliament as an unpaid intern for Andrew Dismore, the Labour MP for Hendon, north London, for six months. He covered my travel expenses, but I had to buy my own lunch.

I was in Parliament three or four days a week, earning money by working in a pub in Stoke Newington during evenings, weekends and my days off.

It was a pretty grotty time, all-in-all, but I was in the same boat as hundreds of other graduates desperate to get a job in politics, either as a Parliamentary researcher or at a think-tank.

And it paid off for me – eventually – as I was offered paid part-time work in Dismore's constituency office and later got a job with the Labour pressure group, Progress.

My internship was dry: endless photocopying, filing and letter-writing, or responding to the piles of invitations.

Dismore received and wrote hundreds of letters every week. If a constituent wrote to him with a concern, no matter how small, we would have to file the original letter and forward a copy, with a covering letter to the council or local hospital. We would then do the same in reverse when we received a reply. Ad nauseam ...

It did seem unfair that I wasn't being paid; I was doing much the same work as his two paid staff, such was the volume of correspondence, and that didn't include the two others who worked in his constituency office, which dealt exclusively with assisting people with their immigration and asylum claims.

I would speak to other interns who were fine with how they had been treated, but others who had never been offered even to have their expenses reimbursed by the MP that they worked for. Some had been promised expenses but were reluctant to ask for it.

Many MPs use unpaid interns in their offices; their workload is often huge, and their allowances for staff costs are limited. You can see that there are conflicting pressures on them, especially now, given the expenses scandal and the recession, not to spend too much public money.

There are familiar arguments in favour of internships: it can boost a young person's CV while they're on holiday from school or college and help them prepare for the world of work. And the employer benefits from having someone around to do admin tasks – and make the tea.

On the other hand, using unpaid interns can be exploitative, if they are doing similar work to paid staff, which, in my experience, they often are.

Not paying people favours rich kids whose parents can support them while working unpaid. And it shows – the vast majority of people who I met working in the Westminster village were white and middle class.