Paul Ransom, founder of Into The Garden Room, installs bespoke garden spas and saunas in and around south-west London. He says inquiries have more than tripled. “Some people are spending serious amounts of money on their gardens now,” he adds, saying the baseline cost for a properly built garden sauna is about £50,000. Recently he designed and installed a sauna, gym/dance studio and wet room in a Richmond garden for £175,000, but even that is small change compared to one lavish garden spa in Hampstead in a project by interior design studio Black & Milk, which cost £1million.