The motion, proposed by May McCreaddie of Greater Glasgow branch of the RCN, called for cleaning services to be brought back in-house.
It follows on from a similar call at Unison's Health Care Service Group conference earlier this month. She said: 'Domestics are an integral part of the ward team.'
Ms Mcreaddie referred to a former in-house cleaning colleague called Betty who used to scare nurses with her incompromising approach. She told delegates: 'We need to bring back Betty!'
Dominic Walsh, a medical admissions unit manager at Royal Free Hampstead NHS Trust, backed her comments.
He said standards of cleanliness are high and infection rates at the hospital are low because of the professional relationship with in-house cleaners, adding: 'I know the names of all the cleaners on the ward.'