Horrible news. He was very ill some time ago, then had a heart bypass op as I recall.
For those that enjoy that sort of thing, there is a cracking 1 hour TV Doc "Hello Quo", the whole Quo story, told mainly in interviews with Rick & Francis.
He had quadruple bypass surgery in the late 90s and two heart attacks in the naughties but he continued to drink and smoke heavily despite severe warnings from the doctors.