THE Tenant Farmers' Association is taking a major campaign on behalf of its members to 10 Downing Street.

A meeting is planned with Prime Minister Tony Blair in an attempt to bring about changes in 54-year-old legislation which bars many tenants from following Government policy encouraging farmers to run operations other than growing crops and keeping animals.

TFA leaders on a tour of the North-East on Monday voiced their disappointment at a Court of Appeal ruling last week which prevented a member from operating an open farm.

A Gloucestershire couple had developed a successful venture which had attracted thousands of schoolchildren since it opened in 1988. It had to close, however, when their landlord served notice that they were in breach of their tenancy agreement, which allowed only agriculture on the holding.

Although an application to the county court overturned the landlord's notice, his case was upheld when he appealed to the higher court.

TFA chief executive George Dunn said at Boroughbridge on Monday that the organisation wanted tenants to be on a level playing field with owner occupiers.

National chairman Reg Haydon, who farms in West Sussex, said 35pc of farm land in England and Wales was tenanted, meaning that a third of the industry was constrained by law from taking part in diversification and agricultural environment schemes.

Mr Haydon said the narrow definition of the term had been incorporated in the 1948 Agriculture Act, when improvements in food production were being sought after the war, and continued in subsequent legislation including the 1986 Agricultural Occupancy Act.

''The 1995 Agricultural Tenancies Act was intended to solve a lot of problems. It introduced user clauses within the rent document and it was hoped that landlords would be flexible, but bitter experience in the TFA has been that nearly always in the user clause it says agriculture only.

''The Government wants flexibility for all farmers to do whatever they want. Some landlords have let tenants get on with this, but the fact remains that there is a law which constrains most tenants."

Mr Haydon said the report of Sir Don Curry's policy commission recognised the problem. Margaret Beckett, head of Defra, and farming and food minister Lord Whitty had listened sympathetically to representations from the TFA and a meeting was planned with Mr Blair on March 26.

Mr Dunn said: "We have been talking about this for six years and lobbying very hard for the last two months."

Mr Haydon said the TFA wanted open-ended user clauses and tenancies of at least ten years, compared with the present average of about four years, with tax incentives to landlords for the longer terms.

The TFA was disappointed that the Curry report had not proposed a retirement scheme, estimated to cost £250m over ten years to run.