By Andy Silvester Just as the arrival of Shein onto London’s equity markets, and the Raspberry Pi float, are more indicative of individual company circumstances than a wider trend, so too would be Ashtead’s departure from London – if they choose to move ahead with it. This is a company after all which, though listed in the capital, makes almost all of its revenue overseas; it even sells in this country under its Sunbelt brand, which is headquartered in South Carolina. Just as Flutter’s departure told us more about that brand’s ambitions and the new legislative landscape of the US than it did L…