According to British History Online, it was on Ely Rd and used as an RAF hospital:
"The Grange, Ely Road, a house built about 1855 by Canon Sparke of Ely, and later occupied by the Hope family, was used in 1914-18 as a home for Belgian refugees and later for the internment of German prisoners of war. In 1920 it was purchased by the Transport and General Workers' Union for a convalescent home. It has so continued except during 1939-45 when it was used as a R.A.F. hospital."
http://www.british-history.ac.uk/vch/cambs/vol4/pp95-102There is also this response to a question on this site:
http://ww2talk.com/index.php?threads/raf-hospital-ely-1942.52511/"Ely RAF Hospital was built in 1939 to treat staff from the numerous RAF bases in the area.
The site, on Lynn Road, Ely is now named The Princess of Wales Hospital. Used for care of the elderly with a minor injuries centre.
Up until the late 1980's? was still run by the RAF as a District General Hospital for servicemen, their families and the local population.
I understand that during the war an overflow annexe was established at a large country house, The Grange, Ely Road, Littleport. A couple of miles up the road.
After the war The Grange was used as a rest home for trade union members and is now a nursing home."
This article from the Ely Standard talks about the staffing of the hospital:
http://www.elystandard.co.uk/ely-life/hospital-s-proud-past-1-246429"Each of the wards was staffed by one or two sisters of The Princess Mary's Royal Air Force Nursing Service who were the only qualified staff.
There were then two VADs (Voluntary Aid Detachments), who had been members of the Red Cross or St John Ambulance before the war. They were given rudimentary training alongside the three orderlies who completed the compliment of nursing staff. "
So your "Paddy" could have been in the Princess Mary's RAF Nursing Service?