Hi Mr. L,
I've mentioned this a few times, but it's maybe worth repeating.
Men pee slower at night, and immediately after waking up. This is because the internal urinary sphincter is a smooth muscle (as opposed to a skeletal muscle) and is under the control of the autonomous nervous system, not under conscious control. That part of your autonomous nervous system takes longer to wake up than your conscious nervous system, and it's still mostly asleep if you get up for a quick pee at night.
Your case would appear to be more extreme. It may be that your internal urinary sphincter, for whatever reason, is relaxing less that it used to, and combined with reduced effectiveness at night, this takes it over the edge into unsatisfactory operation.
Are you on Tamsulosin? If not, it might be worth asking if you can try it to make night time peeing easier. In this case, you would take it with the last meal of the day. Ask your GP or consultant about this. In theory, you can get it off-prescription for up to 6 weeks, but I would always recommend speaking with your GP or consultant first, to ensure it's not contra-indicated by any other medications or medical conditions. You need to be careful if you take it with PDE5 inhibitors, as they're both uncontrolled blood pressure reducing medications, and can make you faint if they pull your blood pressure too low.