Persimmon's acquisition last October of Kentbased Hillreed Homes merited little more than a brief footnote. Pre-recession, Persimmon gorged itself on the likes of Beazer and Westbury. That such a behemoth was paying £35.7 million in cash for a business with a 3,400-strong landbank was, in news terms, worth little more. What that deal provided, though, was firm evidence that shares …