A lot of men suffer from some numbness on long rides, but this usually only lasts for minutes once they are off the bike. My guess is that you have let it get really bad during the ride, to the point of causing more serious damage and even some minor nerve damage which takes time to recover, rather than just taking a few minutes for blood flow to return to normal. My advice, apart from the obvious of change saddle and try different shorts; would be to lift out of the saddle for a few seconds every few minutes or so. This might just be for a short climb or just for 3-5 seconds on the flat - doing this frequently should help a lot and it will also become habit to the point that you don't even realise that you are doing it and it certainly shouldn't affect your riding either.
I did actually get out of the seat during my ride, but mainly this was to give the calves a good stretching without getting off the bike. I just masured my inside leg, its 37 inches from groin to heel and about 35 from groin to ankle. When you compare this to my height (in cm this time sorry to be annoying) which is about 193, apparently, even though I am quite tall, my legs are too small for my body. (This is apparently a trait of Scots people)
Therefore even though my seat is at the correct height (my knees are slightly bent when pedal is as at the bottom of a revolution), perhaps my handlebars could do with being slightly lower to account for a propotionally longer upper body (arms).
First things first guys, I'll put my new saddle on, tilt slightly at the front and try getting out of the seat every few minutes. But I won't be going anywhere near the bike until full sensation has returned.