Campaigning cleaners were celebrating after securing a pay increase up to the London living wage.
The cleaners for St George's Hospital Medical School, housed within St George's Hospital, Tooting, have been running a campaign for increased pay through posters, leafleting and petitions.
They will be paid a new hourly rate of £8.30 per hour from August 1, an increase from their current wage of £6.08 an hour after UNISON signed a deal with contractors Ocean Contract Cleaning Ltd.
However, trade union Industrial Workers for the World (IWW) have said the cleaners could face having their hours cut, which would make the pay rise futile.
UNISON have denied signing anything agreeing to cuts, with a spokesperson accusing IWW of being an anarchist group.
A protest to raise awareness of the issue was staged by IWW outside St George's Hospital last Friday, May 25.
Cleaners, medical students and families took part to raise awareness staff were being paid below the London wage.
A spokesperson for UNISON said: "We managed to secure the London living wage for hospital staff, but never for the teaching school.
"We have not signed an agreement allowing any cuts, our objective is to secure the London living wage.
"What we want is for establishments in the borough to sign on to the agreement because not all are paying it."
Simon Edmin, UNISON branch secretary, said: "We are pleased that the St Georges Medical School has recognised the importance of paying the London Living Wage it will make a significant improvement to the working lives of many hard-working low paid women workers.
"UNISON pays tribute to the cleaners and St Georges medical students for their role in ensuring that the London Living Wage was fully implemented."
Principal Professor Peter Kopelman speaking on behalf of St George's University of London, said: "This is an important commitment that required careful consideration during the current financially challenging time for the higher education sector.
"The outcome affirms our position to ensure that staff working at St George's receive a fair remuneration that is commensurate with their roles and responsibilities.
"We will work with our contract cleaning company Ocean over the coming weeks to put the new arrangements in place by the University’s new financial year."
Petros Elia, spokesperson for IWW, complained Ocean Contract Cleaning Ltd were only giving recognition to UNISON over the pay dispute.
He said: "They are carrying heavy things, not wearing the proper gloves and don't have proper cleaning equipment and not given more pay for deep cleaning."
Mr Elia said there were plans to flyer outside the hospital again this week and push awareness for recognition of the IWW.