"It's going to slow things down; it's going to make things more expensive; it's not going to deal with the issue of gazumping or gazundering; it's not going to help first-time buyers.
"We need to alter the way in which we buy and sell houses in this country. There is no doubt about that. But the HIP is not the way to do it."
The implementation of the packs comes after the Government was forced to delay the introduction of Hips from June to August following a legal challenge from the Royal Institution of Chartered Surveyors and fierce Tory opposition.
Housing Minister Yvette Cooper has insisted today that HIPs would help make house buying speedier by requiring the seller to compile information at the outset.
She also said the energy performance certificates (EPCs) in the packs would play a role in tackling climate change by showing home-owners how to cut fuel bills.
But Miss Allsop dismissed the environmental argument for the packs, saying that home owners were already eligible for energy saving grants and that Government could have included the EPC part of the HIP in existing home surveys.
The regulations which apply from today mean that anyone putting a property with four or more bedrooms up for sale in England and Wales must compile one of the packs, which will include EPCs, standard searches and evidence of title.
"The majority of people who have houses of four bedrooms and over are older people, looking to maximise the value of the houses they have invested their life savings in," Miss Allsop said.
"It may only be 20% of the houses for sale, but it's those people who are most easily confused that are going to have to deal with this first implementation of the Home Information Pack."
She added that homeowners may be able to avoid having to compile the packs by removing a bed from a fourth bedroom and selling it as a three bedroom property, with a study.
The Channel 4 presenter called on the housing minister to rethink her approach.
"If the Government could sit down and say there must be a better way of making it easier for people to buy and sell houses then I think we'd all be really happy to talk to her.
"The problem is that soldiering on with this and ignoring everybody's issues and pretending they are the only people who know how the housing market works is not the way forward."
She added: "The people who are going to lose out is everybody. There's talk of it being £300 to £500, but there's no cap on this."
Mike Ockenden from the Association Of Home Information Pack Providers also attended the event and gave an opposing view.
Carrying a placard that read "Listen to Kirstie and lose a buyer" he said that HIPs would not only help both buyers and sellers, but would save them money as well.
"It's a very simple concept, you just take the information gathering process from after somebody's had an offer accepted and put it in front.
"It speeds the transaction up, the consumer is more aware of what they're buying, what they're putting in an offer for, reduces all the stress associated with the uncertainty long transactions take and ultimately saves money."
A spokesman for Communities and Local Government also maintained that HIPs would save consumers money.
"The introduction of HIPs is already leading to search prices coming down for consumers, with nearly fifty local authorities having already reduced what they charge consumers for searches, in some cases by more than £100."
He added: "The Government will monitor HIPs closely to ensure the benefits are being passed on to the consumer, with a new consumer panel being set up as part of a wider programme of action to make the home buying and selling process work in the interests of consumers."