(Bloomberg) -- British homebuilder stocks are flashing a key buy metric for the first time in more than a year, indicating a possible end to a slump spurred by concern that elevated mortgage rates will hamper demand.Most Read from BloombergHong Kong's Expat Party Hub Reshaped by Chinese InfluxHow California Sees the World, and ItselfLondon’s Tube Fares Are Set to Rise by 4.6% Next YearThe Bloomberg UK Homebuilder Index is trading at a price-to-book ratio of less than 1, loosely meaning the equit