Union leaders have hit out at the Mayor of London after he seemed to suggest he didn't know how many staff were being cut at the famous Royal Botanical Gardens.

The candidate to be Uxbridge and South Ruislip's next MP was in Singapore at the weekend to boost its bid to gain World Heritage status - identical to that held by Kew.

Prospect has been battling to safeguard jobs ever since the Government began cutting grants and other sources of funding.

The 121 hectare site has already lost 65 of its 244 scientists and last Friday a further 51 were told by email that they are also surplus to requirements.

During an interview with BBC London Mr Johnson was told about the latest cuts but responded: "You're bringing up something that hasn't been raised with me here by anybody from Kew...but clearly I will take it up now that you've mentioned it.

"I would not like to see a great London institution suffer from damaging cuts to its research base. You can easily damage a vital resource."

He was shown a collection of rubber trees which were first introduced to the region by Kew in 1877 and from which most of the world's supply are descended.

He added: “Singapore’s relationship with one of our most quintessentially British brands is testament to the huge appetite there is for London’s expertise overseas. I think it’s absolutely stupefying. What was so amazing was to see the connection between London and the Singapore botanical gardens.”

Prospect negotiator Julie Flanagan said: “The Mayor of London is well aware of the situation at Kew. He must have had a memory lapse between London and Singapore.

“It’s great that the mayor is backing Singapore Botanical Garden. Let’s hope he can now step up to offer the same support for the world-leading botanical garden in his own back yard – Kew.

“Losing hundreds of years’ worth of experience by making people redundant and then recruiting 40 external staff while saying how critical Kew’s finances are just doesn’t make sense.

“We are urging Kew to let the new structure bed down before making any more redundancies.”

Kew Gardens

A meeting was held in Kew on October 22 at which local politicians and union representatives vowed to lobby the Government hard to recognise the garden's incredible contribution to everything from controlling global climate change to reducing world hunger.

Hayes and Harlington MP John McDonnell tabled an Early Day Motion on Tuesday (2) - currently signed by 8 other MPs - in which he states the House of Commons was appalled at the recent job losses which will 'result in the loss of over 1,000 years of scientific expertise' and 'and calls on the Government to urgently halt these further redundancies in order to allow the new structure put in place at Kew to take effect and to fully engage with staff and unions in order to save as many key scientific posts as possible.'

The House of Commons Science and Technology Committee will examine all details surrounding the funding cuts when it meets on December 17. Kew's director Richard Deverell and Defra minister Lord de Mauley are both expected to attend.

A Royal Botanic Gardens, Kew spokespersons said, “51 staff members have not been appointed to a role in the new Science structure (which began on Monday (1))

"However, there remain 42 vacant posts in the Science structure. A number of colleagues who are yet to secure posts have skills that we do not wish to lose, as such, as a next step we will have an additional round of ring fenced recruitment which is only open to those staff members who have not been appointed at this point.

"Therefore, it is likely that this figure of 51 will be reduced, and fewer staff will face redundancy. The additional ring fenced recruitment is part of our redeployment commitment to reduce redundancies.”

The restructuring of Kew's staff began in April this year and is expected to be completed by March

Mr Johnson was yesterday caught up in an air-rage incident as he returned to Heathrow from his Far East tour.