By Charlie Conchie Activist investors are circling the London Stock Exchange this year in a bid to capitalise on the “significant valuation gap” facing UK firms, a new report has claimed. Alvarez & Marsal, the consultancy firm, found that the number of UK-listed firms susceptible to a swoop from activist investors had increased to 54 this year, making it the most ripe destination in Europe for campaigns by investors. Activist investors typically quietly build a stake in companies before emerging with a list of demands which they argue will boost its performance and value. London has seen a sle…