People are officially insane

Invitations were a bar of chocolate with a bespoke printed wrapper and a golden ticket inside. Every seven-year-old in the country was desperate to receive one. Those who did not were inconsolable.

On the day itself, the lucky few were brought up the drive of the Gloucester stately home in candy-coloured golfcarts. Inside the circus tent on the back lawn was an acrobatic Willy Wonka and his troupe of oompa-loompas, who performed every half-hour.

'There were three chocolate fountains, one with marshmallows, one with strawberries and one with biscuits,' said Caroline Hurley, director of Quintessentially Events, who organised the party earlier this month. 'We also installed a giant gobstopper pond as well as circus games, a miniature bumper-car track and a carousel.'

Parents were plied with champagne and canapes, and each of the 30 children was given a party bag bulging with sweets before they left. The total cost of the party was £20,000.

Children's birthday parties once meant a slice of cake, a bowl of jelly and a quick game of pass-the-parcel at someone's house. Now parties are more of an annual exam for parents. 'Children's parties have become the acme of competitive parenting,' said Hurley. 'It's not unusual for 60 children to be invited and the cost to reach £50,000.'

According to recent research by sweet-maker Haribo, even the average family forks out £129 for their little one's special day. Flora White, of Concierge London, regularly sees parents spend far more. 'We have organised children's parties costing £250,000,' she said. 'We've held football tournaments where the “coaches” were well-known footballers. We also flew a West End musical star across Europe to sing “Happy Birthday” to a 13-year-old girl.'

The BBC is dedicating a new six-part series to this phenomenon: on Tuesday evening The Madness of Modern Parenting looks at how even the most sensible parent gets sucked in.

According to Illana Salem, whose sons Sammy and Louis are 10 and seven years old: 'It's like the speech day of parenting: it's your moment to shine, to prove what a fabulous parent you are. It's the moment when you're judged. I suppose it's like a dog show.' Besides finding the perfect venue, parents have to decide who to invite, which entertainers to book and what food to serve. 'Proper children's party food is full of E numbers and illegal colourants. But junk is bad; the food of hoodies,' said Salem.

In all this, the children themselves are often forgotten. 'We were invited to a party and it was so much about impressing the parents that the kids got forgotten completely,' said Jo Haywood, who lives in York with her seven-year-old son Jack and daughter Mia, aged three. 'There was no food for the children at all. At three o'clock we left and went to a Little Chef.'

And what of the entertainment? Stephen Rowlings, who runs exotic animal company Tropical Inc, said he believed competitive parenting was at the heart of the surge in demand his company has seen. 'In the last two years, I have gone from doing no children's parties to doing eight every weekend,' he said. 'Parents are desperate to throw the biggest and grandest parties.'

And when it seems to be all over, there is the final test: the party bag. 'That is how the other parents are going to judge you,' said Haywood. 'In that one tiny bag they are going to form a picture of your whole lifestyle.' On www.mumsnet.com, entire conversation threads are dedicated to this thorny issue. 'My two went to a party where everyone got sent home with a goldfish!', one wrote.

The only way to resist the temptation to compete is, it seems, not to throw a party at all. 'We've done the fairy party, the bouncy-castle party, the pottery party, bowling party, disco party and the Brighton Pier party,' said Gina Deferrer, whose daughters Olivia and Isabelle are 12 and nine. 'Then last year I thought, “I really can't cope – we're going to go abroad!” So, yes, we went to France just to get out of doing a birthday party.'