Something that works really well in London, and might work well in big urban areas, is partial WFH. If someone can work at home 50% of the time, they can live 5 hours away and just come in on a Tues morning, leave on Thurs eve, or are willing to put up with a 2 hour commute as they only do it half the time. I managed a mid-sized tech team at a company that did this, and it gave us access to many many candidates who didn't want to live in London, but lived as far away as Edinburgh...