LONDON (Reuters) - Want to cheat on your partner? Need a cast-iron alibi? Then ring entrepreneur Ronnie Brock. "Infidelity is alive and well and kicking. If you want to swing, give us a ring," says the former rock musician whose cheating hearts club has turned into an international gold mine. Within three months of setting up The Alibi Agency, Brock has acquired 8,000 eager clients. His brainwave is deceptively simple like all the best business ideas, but marriage counsellors have slammed it as immoral. For 20 pounds, you join the agency, signing a disclaimer if it all goes wrong. Then you take your pick from the assorted services on offer. For 25 pounds, the agency can invite you to a bogus business convention and mail the letter to your home. The agency even arranges for fake hotel receptionists to answer the phone when a husband or wife rings up. The cheaters can get fitted with a discreet humming pager to alert to them to a call from home. So far, Brock boasts a 100 percent success rate. None of his clients have got caught. Marriage counsellors have accused Brock of setting up a destructive service that undermines the sanctity of marriage, but he dismisses such charges. Up to 40 percent of his clients are women. Brock claims that the agency is actually protecting married couples. The Alibi Agency certainly has to keep its antennae up and alert. "We get lots of wind-ups. We had one guy from Jamaica on the run from police who wanted me to give me an alibi. I told him where to go. We have been asked to provide alibis for people doing bank jobs. But we do nothing criminal."