Rural Britain took over central London today in the biggest invasion of its kind ever seen.

The Countryside Alliance Liberty and Livelihood rural rights march was tonight described as the biggest protest of any kind in the UK after at least 300,000 demonstrators converged on the capital.

Following months of organisation the Countryside Alliance said the march was a huge success and it called on the Government to make a ''considered response'' to the concerns highlighted by the protest.

Marchers from across the globe set off from Hyde Park Corner and Blackfriars Bridge for Parliament Square where the Metropolitan Police and Alliance officials recorded the numbers taking part.

The police tally ran at 300,000 while Alliance officials said 400,000 had taken part. Conservative leader Iain Duncan Smith was near the head of the march which set off from Blackfriars and was one of a number of high-profile people adding their voice to the Countryside Alliance message.

''I think this is a statement by those in the countryside and many others in towns and cities about how this Government tells people how to live their lives - but is not addressing the major issues and problems they are facing,'' he said.

''The whole spectrum of countryside problems, transport, the closure of hospitals and rural schools and so on.

''And yet they want to ban hunting and they are prepared to give Parliamentary time to that.''

Around 20 roads in central London were closed to traffic as the march got under way with 1,600 police officers on duty and an extra 1,800 stewards from the Alliance on patrol.

Five giant screens were erected along the route to show live pictures of the marchers, coupled with a ''counting zone'' in Whitehall to give a live running total on the numbers marching.

The marchers arrived in London on 31 specially chartered trains and a further 2,500 coaches.

Speaking at the end of the march, Mr Jackson said: ''It is absolutely huge. By a mile, it's the largest march for a demonstration of any kind that this country has seen.

''As a proportion of the population, it has become very, very interesting. Anybody who thinks that this is just about hunting must be living on a different planet.''

He added: ''If the Government make the mistake of doing something unjust, I have no doubt that the countryside will erupt in fury. There is a simmering anger out there.

''If the Government does proceed in a sensible way towards the countryside, they will also find that there is a well of co-operation.''

Mr Jackson said a delegation from the Countryside Alliance would also be delivering a 10-point open letter to the Prime Minister at the end of the march.

The Alliance now plans to hold a conference within the next 40 days with a view to setting up a rural council on a par with the TUC and CBI representing the ''whole of the countryside''.

''The countryside needs a rural council,'' said Mr Jackson. ''Such a unified representation is long overdue.''

He added: ''The Government responded 18 months ago to the countryside's calls for a department of rural affairs with the creation of Defra. It is clear that Defra needs a partner which speaks for all rural stakeholders.''

The conference will probably be held at Stoneleigh, Warwickshire, where the Royal Agricultural Society is based.