Del Carmen First St Joseph's College, Mill Hill, London

Completed in 1866, St Joseph’s College was once a grand, sprawling seminary for training priest and missionaries (it also once doubled for a convent in ITV’s Call the Midwife) – but by 2008, the last of the clergymen had left, and the stately complex lay abandoned.

Developer Berkeley Homes quickly recognised that the site had huge potential, and got to work transforming it into 49 luxurious apartments set in seven acres of mature parkland, and just ten miles outside central London.

It was a major task for a number of reasons – not least because the site was in sore need of a facelift, and carried a Grade II listing.

The roof posed a particular challenge. They needed a material that looked authentic, offered superb performance, could be supplied in large quantities and that came at a competitive price.

Together, that made SSQ’s Del Carmen natural slate the most attractive choice. The celebrated material had already doubled for indigenous slate on dozens of prestigious buildings, and impressed geologists and conservation officers around the country.

Thanks to SSQ’s long and successful partnership with North Spain’s Del Carmen quarry, the development was guaranteed a consistent supply of outstanding slate.

The project went on to receive a much sought-after National Federation of Roofing Contractors Award.

Del Carmen First St Joseph's College, Mill Hill, London