When the cheapest flats cost pound;80,000, buying a home was out of the question. He had been considering leaving London because he was sick of paying pound;550 a month out of his pound;25,000 salary to live in a small flat several miles from his school.
But, for the 40-year-old, things may be about to change through a pilot scheme to provide affordable homes for teachers.
He is one of 80 teachers in the borough of Southwark hoping to get on the first rung of the property ladder with a "shared ownership" scheme launched by the council and Landmark Housing Association.
Mr Mutumba wants to use the scheme to buy a share in a new two-bedroom house in Peckham just a short walk from Walworth school where he works.
Under the scheme, hecan buy a 35 per cent share of a pound;145,000 house and pay rent on the remaining 65 per cent - in total this will cost only pound;566 a month.
"Finding somewhere reasonable to live is one of the most difficult things to do in London. My flat is 15 minutes' drive from school and is very small. I really need a bigger place. I have a daughter from a previous relationship and it is difficult to have her to stay as much as I would like because my flat is so small."
Competition for the 11 new homes on offer will be intense. Any teacher working for Southwark council can apply but applicants from schools with the biggest recruitment problems will get priority.
Southwark launched the scheme with Landmark after a survey found that nearly half of the borough's teachers wanted to buy a property near their school but could not afford it.
For details call Landmark on 020 7501 2000