Today, my wife and I both visited Derek again and are happy to report that he is a lot better than yesterday. He's back on controlled doses of morphine - which proves that he really was showing withdrawal symptoms. While I stayed for about an hour, my wife spent an additional two with him. They went to the hospital's retaurant patio - and had a good discussion about things (big bands,various kinds of music, the inventors of overdubbing and multi-channel recording, Les Paul and Mary Ford, etc...) totally unrelated to Derek's fight with the cancer. It was Derek's first time in the open since his hospital stay began.
Derek is now going to follow a regimen of gradual morphine withdrawal, with lower and lower doses stretched over longer and longer periods. This should go on for about a week. Most of this is likely to happen at his home - we'll provide whatever needed support we can help with. This includes looking after our grandsdaughters - not a chore in any case; we love having them at our place.
Things are looking up again.