A legal challenge to the health campus scheme is "a real issue" for the project and could have "consequences" for the town, Watford’s elected mayor has warned.

Dorothy Thornhill said if a second judicial review of the decision to allow the Farm Terrace Allotments to be used in the development scheme succeeded it would affect the hospital, taxpayers, and future residents.

The mayor said: "It is a real issue and I don’t think we have really made enough of the consequences (if the judicial review is successful).

"There will be consequences if that happens for the revenue to the public purse in the future and to the viability of the scheme. It would also restrict the flexibility of what the hospital can and can’t do and affect the density of the properties

"There are very clear consequences that people have not factored in. They see it as a David and Goliath but in fact I am speaking up for thousands of little Davids: The future residents of those homes, the hospital and the taxpayers who will be grateful for the revenues it will generate.

"They are putting all that at risk by making it less viable."

This is the second time allotment-holders have challenged approval given to Watford Borough Council by the Secretary of State for Communities and Local Government, Mr Pickles, to build on Farm Terrace.

Last year Mr Pickles reversed his initial permission to reconsider the decision after Farm Terrace Community Association took it to judicial review.

Watford Observer: Farm Terrace Allotments.

However in December he granted the council permission to build over the allotments for a second time, as part of the scheme which promises to regenerate the land behind Vicarage Road with new hospital facilities and around 700 new homes.

Earlier this month the group launched a judicial review of the second decision.

Solicitors working on behalf of the Farm Terrace Community Association are arguing the council "misled" the Government over how crucial the allotments were to the new hospital element of the scheme.

The group has pointed to a health campus masterplan, which they say shows most of the land being used for new homes and parking for Watford FC.

Watford Borough Council has since confirmed 40 per cent of the allotment land has been earmarked for hospital use.

Watford Observer: The latest health campus masterplan.

Mayor Thornhill rejected the basis of the new challenge as "completely wrong" and said the fact the Government was holding its ground this time round was an encouraging sign.

She added: "We have made a robust challenge. It think it is important as this time last time (there was a judicial review) the DCLG caved and they have not (this time). I take that as quite a strong signal."

The Farm Terrace Allotments had been protected in previous versions of the health campus scheme, which has been under discussion for more than decade.

However in 2012 Watford Borough Council’s ruling cabinet voted to include the land in a new version of the project saying it was needed to make the scheme viable for developers.