The final member, Sir Chris Gent, made an unassuming return to the FTSE 100 late last year as chairman of ConvaTec, which in October became London's largest initial public offering since Worldpay and its biggest healthcare float for at least two decades. With a £4.8bn market value, ConvaTec was admitted to the top flight in the December reshuffle. Glamorous it is not. ConvaTec specialises in colostomy bags, catheters, complicated dressings and insulin tubes.