The buy-to-let market is fracturing along regional lines as landlords respond to a punishing combination of higher borrowing costs, tighter regulation and stagnant capital growth in the South. New portfolio data circulating among letting agents and mortgage brokers this week shows a clear pattern: investors are selling out of London and the South East, where yields have compressed to below 4% in many boroughs, and redeploying capital into Northern England, where gross yields of 7% to 9% remain achievable in cities such as Liverpool, Newcastle and parts of Greater Manchester. This is not a marginal adjustment. It represents a structural repositioning of one of Britain's largest asset classes, with implications for house prices, rental supply and mortgage lending patterns that will play out over the next several years.