Dudley House, 100 Park Lane

At 44,000 sq ft, it is more than 42 times bigger than the minimum size for a three-bedroom house in London required under space standards introduced in the capital last year. Sheikh Hamad has spent an estimated £10m alone on transforming the original three buildings, including the headquarters of the property firm Hammerson, into a single house. Experts believe the renovation may have cost £75m in total.

TRC carried out refurbishment of the windows at Dudley House, 100 Park Lane.