WHAT started as plans for a birthday party among few friends escalated out of control this week when 21,000 people signed up to the event online.

A Harpenden teenager thought to be in Year 9 at Sir John Lawes school posted details of the house party – which was planned for Thursday, October 7, – on Facebook complete with her address and phone number.

When more than 21,000 people signed up for the event – which is taking place at a location in Harpenden we have chosen not to name – the posting was taken down, but since then a number of spin-off groups have popped up on the social networking site and have re-posted the address.

One of the event pages insists that the party is still going ahead and nearly 7,000 people have accepted the invitation with more than 1,270 people putting themselves down as ‘maybe attending’.

The page has attracted a huge number of fake celebrity followers – including Justin Bieber, Stephen Hawking, Stevie Wonder, Susan Boyle and Rick Astley – who have all posted messages on the page.

The teenager’s concerned mother has even posted a message on the page telling people the party is cancelled which was met with a tirade of highly offensive abuse from some members of the event group.

Other groups have been established inviting people along to a pre-party, after-party, clear-up party and ‘hang-over’ party and several people have also attempted to mimic the teenager’s profile to post messages on the various groups claiming that the party is going ahead.

One concerned Harpenden resident said: “More people than the population of Harpenden are supposedly attending and thus we are very concerned for our small and humble town on October 7.”

The police have now been called due to fears that thousands of people will descend on the small street.

Harpenden Neighbourhood Sergeant Lewis Ducket said: “We are aware of this and have been assured that the event is no longer taking place. I would urge people who may be planning to come to Harpenden for the party to make other plans. We will have officers on patrol in the area on October 7 to provide a reassuring presence and who will be able to deal with any issues, should they arise.”

Anyone with any concerns can call the neighbourhood team on 0845 3300222.