Towing a motorcycle - artful dodger {P}
Over the weekend I saw a car towing a motorcyle. Nothing unusual you might say if it was on a trailer. No it was being towed using a rope about 20 feet long. It looked highly dangerous to the rider and other road users. My question is was this illegal?

No I did not get either registration number as I was driving in the opposite direction.
Towing a motorcycle - Dynamic Dave
No idea if it's illegal or not, but my Uncle once bought a 70cc Honda motorbike from Oxford, and asked me to ride it home for him as he had his car and my insurance policy at the time covered me to ride other motorbikes as well as my own. Half way along the A34 the chain snapped and I ended up being towed by my uncle's car. Within a mile he had forgotten that I was attached to his car and the bikes speedo went off the clock. I tried attracting his attention in his rear view mirror by waving frantically, but everytime I took one hand off the handle bars the bike developed a speed wobble.
Towing a motorcycle - BazzaBear {P}
I know of someone who once had a tow from a car, he was, co-incidentally, on a Honda 70cc 'bog-seat' (that's what we always used to call them anyway, due to the way you accessed the petrol tank). He ended up being dragged along the road on his side for a reasonable distance. Luckily no injuries sustained, but it's not the most sensible thing ever, I don't think.
Towing a motorcycle - SlidingPillar
As far as I know, towing a motorcycle is only legal with another motorcycle.

Tow ropes over 1.5m have to be marked, and the maximum length is 4.5m. So 20 foot is naughty too.
Towing a motorcycle - keo-the-dog
you can tow a bike but only with a bike of equal or greater engine size and the tow rope cannot be tied to the bike which is being towed you have to be able to un-attach in an emergency . usually thi involves feeding the towrope through the forks and up to the handlebars where it may be looped round the grip and held in place by the riders hand pressure, meaning if you let go the rope will slide away. i have been towed like this some years ago and i assure you it works although it is not a pleasant experience nor in my opinion a particularly safe one. ...cheers...keo.
Towing a motorcycle - Robin Reliant
I remember towing a mate on his Bantam from East Ham to Rainham, about ten miles. The rope was looped round the forks of the bike and tied to my Reliant's bumper. A proper steel bumper, none of this colour coded tissue paper rubbish like todays stuff. We went along the A13, which was an adventure in itself. Because the rope was round the forks the handling on the bike was compromised somewhat, and the roundabout at The Volunteer in Barking was taken amid much weaving and arm flailing on his behalf. I decided that the next roundabout, the oblong shaped Thatched House was best avoided so took the flyover instead, managing to get over forty to try and keep the artics from sweeping him up.

He had no gloves on and by the time we got to his house his hands were bleeding from his desperate fight to keep something resembling a straight line. It was rather frightening to see him bobbing and weaving in the mirror because we were clearly an accident waiting to happen, but I solved that problem by not looking in the mirror after about half distance. When we got to his house I remarked that I would not fancy doing that again. He replied with "YOU wouldn't $%!*&%£ want to do that again?"

That was about twenty seven years ago, and the Bantam is still lying untouched in his garage, awaiting a restoration project.