John Lord has been in previous trials for the male pill. He had a pretty strong reason for taking part: he and his wife had an accidental pregnancy.

"I got pregnant with my third child on the female pill and it came on the telly that a doctor was doing these trials in Manchester, so I nagged him to come and do it," he says.

Even if an effective male pill were available, there is a feeling that many men would simply refuse to take it; contraception is regarded as a female responsibility - but not for John.

"I didn't mind doing it. I don't mind - she's been taking the pill for quite a few years, she had all these side effects, so I knew it'd be nice for her to have a break and me take a bit of responsibility too."

Even so, taking it and admitting to it are two entirely separate things: "I did keep it quiet, I didn't mention it much to anybody. In fact I didn't tell anybody, full stop."

A question of trust

However, John Lord did trust the researchers at St Mary's Hospital and the University of Manchester, but now confesses to being a little afraid that anything that interferes with his ability to make babies could also make him effeminate.

Dr Fred Woo thinks he knows why previous trials did not work

The good news is that the pill now under development uses the male hormone testosterone.

Dr Fred Woo is leading the research: "What we do is to give these male hormones to men, which will fool the pituitary into believing there's more than enough sperm present so the pituitary gland stops producing this work signal for the testes and sperm production is stopped."

Previous trials found that the pill only worked for two-thirds of the men. In the others a few sperm survived. No-one could explain why.

Dr Woo now thinks it is because of another hormone, prolactin. It is not known what it does in men, but he thinks it kicked in after the testosterone worked and began manufacturing sperm.

"We believe that if we can suppress prolactin we can get rid of those few sperm that are still remaining and therefore make the method nearly 100% effective," he says.

Healthy volunteers

Dr Woo needs to test his theories. He is appealing for 60 healthy men to take a daily pill and wear a small implant for four months.

The research team now requires volunteers

"There are some side effects when we're using higher doses than we're using at the moment. So we're quite confident that with the reduced dose, and particularly with the newer formulation that we're trying, the side effects can be restricted to a very small minimum."

Once the trials are finished, the pill will go on the market - maybe in about five years.