By Muvija M and Aiden Nulty LONDON (Reuters) – As a drizzle fell over a grey autumnal London, and the pound plummeted on traders’ screens, U.S. tourist Heather Davidson saw one gleaming bright spot on her horizon – the chance of ever cheaper treats in Covent Garden’s boutiques. Across town, the capital’s financial district was still reeling from the impact of new finance minister Kwasi Kwarteng’s tax cuts which, as the biggest since 1972, will be funded by huge government borrowing. Sterling plunged after the cuts were announced on Friday and fell again on Monday to a record low. A lot for the…