Sales of properties in London’s prime neighbourhoods slumped last month as the UK government's budget put a pause on transactions, figures show.There were 17.5 per cent fewer sales transactions in October than a year earlier, and 6.6 per cent fewer than the October average for the pre-pandemic years of 2017-19, according to figures by property data firm LonRes. The number of sales was the lowest in any October since 2018, LonRes said. Prime…