Weeing on sofa!

Help! Our lovely bun is two and a half and neutered. He started doing the occasional wee or poo on the sofa about a year ago and in the last couple of months it's got so much worse. He'll do it on the side that I sit on (if I'm not sat down) and will jump up and do it beside or on me if I've fallen asleep there. Over the same sort of period I've had him running at my feet a lot. My husband foesn't get the same treatment so essentially I think he's trying to show me that he's top bunny of me. I've nearly stopped the charging at my feet by standing my ground and walking purposefully towards him after he's done it. But the sofa issue remains! When he does it I soak up any wee and spray white vinegar. Deterrents I've tried are:
Putting metal grids in the sofa - helps but he can move them..!
Putting a foil blanket on the sofa. He usually hates scrunching noises but he just wee'd on this.
Saying 'NO' firmly when I catch him doing it.
Moving him as soon as I see him jumping up there.
Any ideas? He's wonderful apart from this! I'm having to put blankets on the sofa and am washing two or three a day at the moment

Restricting buns' area for a while, or putting an extra litter tray on the sofa may work. If you catch him doing it, then restricting him to his pen straight away would work better than randomly restricting him. Has anything changed recently that might have upset your bun? Using a new body lotion, scent; changes to routine, new item in home... Things like that can sometimes trigger unwanted terratorial behaviour. We've had the problem after either acquiring an item we think came from a home with another pet (the remote control buttons had been chewed off,) or because I'd tried on some scent in Boots that day! Also when I had to start treating her again for sore hocks after there'd been a break in the routine. Both occasions triggered a bout of repeated weeing on bed/sofa, when normally she is well behaved. You can also get plastic car seat protectors in Pound shops, you could try putting over the sofa with a throw over it. Then at least if he does it again, there's less chance of the wee going through to the cushion seat. Putting down puppy training pads works for some buns also, unless you have a bun that likes to eat them like mine!