Children’s birthday parties used to be modest affairs – a couple of games of pass the parcel followed by a plate of jelly and ice cream.

Not any more. Today’s generation of competitive parents are dipping ever-deeper into their pockets to make sure their offspring have the best day money can buy.

A family in Gloucester spent £20,000 on a Willy Wonka party for 30 children, complete with a troupe of Oompa-Loompas who performed every half-hour, three huge chocolate fountains and party bags bulging with gifts.

Another family organised a football tournament featuring professionals as coaches and one parent flew a West End musical star across Europe to sing Happy Birthday to a 13-year-old girl.

A survey has revealed that the average family spends £450 every year celebrating their children’s birthdays. The poll by American Express also found that one-in-10 families admitted throwing parties just to impress other parents.

Caroline Hurley, of Quintessentially Events, which organises functions for business, said: “Children’s parties have become the acme of competitive parenting. It’s not unusual for 60 children to be invited and the cost to reach £50,000.”

In the United States, the scramble to stage ever more extravagant events has led to the creation of a pressure group calling for an end to excessive birthday bashes. As reported in yesterday’s Daily Telegraph, Birthdays Without Pressure is attempting to spark a debate on the social and financial difficulties parties can cause.

A study by Virgin Credit Card last year estimated that British parents were spending £1.25 billion a year on children’s parties. American Express this week put the figure at more than £1.4 billion.

According to the poll, a third named expensive amusement parks as the top choice of party venue. An average family with two children spent £174 on parties, £168 on presents and £100 sending their children to friends’ birthdays. One in 10 said they went to excess to impress friends and families and a quarter of parents were motivated by the experience of having disappointing parties as children.

Research by Haribo, the confectioner, showed that nearly two-thirds of parents admit to feeling uneasy about what other people will think of their child’s party and a third make themselves ill with worry.

Katie Burnett, the owner of the firm Les Enfants, is about to stage a “fashion party” for a 13-year-old girl and 30 of her friends. Her firm is transforming the suite of a London hotel into a fashion show, complete with a cat walk – at a cost of £30,000. “The level of detail required is the same as a large corporate event,” she said.

The trend has attracted the attention of television. The Madness of Modern Families, on the BBC this week, exposed parents who use the party bag to boost their social status.

One parent packed children’s bags with bars of expensive, dark 90 per cent cocoa organic chocolate, which was too rich for them to eat, while another child’s bag contained portable DVD players.

But, such is the demand, many firms have sprouted up offering birthday treats for children. Party Ark – a company supplying equipment for children’s parties – was set up by Alistair Potts. Mr Potts, 35, gave up his job as a web designer in 2005 to start the firm.

He said: “Parents don’t really need to spend ridiculous amounts. When people do go crazy it is on parties at things like theme parks, but most parents can have a good day out relatively cheaply.”