At present, unlike the US, the UK does not require presentation of medical examination certificate for visa purposes.
The only suggestion, as it has mentioned by whiteraven, is to bring along a chest x-ray in the hand luggage, so to save time at airport immigration, in case someone is asked to have x-ray taken on arrival.
Sometimes they do, some other times they don't, it seems to be some lottery.
Although my wife did carry one with her, she was not asked to present it, but a few weeks later on registration at my doctors, she was referred to the local hospital for a scan.