By Ali Lyon A week in which 50 firms posted their final results was always going to produce some news. And news there certainly was as St James’s Place, Reckitt and Halfords shed billions in value and a fresh crop of firms fell into the sights of private buyers. The trio were forced to issue profit warnings to the market and sparked a mass sell-off in shares, while others took investors off guard by revealing unexpected success. All the while, the worrying trend in which bargain-hunting buyers look to London’s lowly valued firms accelerated, with three British businesses falling into the sight…