how about a tow pole http://www.halfords.com/camping-leisure/trailers-towing/towing-accessories/aa-sprung-towing-pole
seems you can't tow cars on motorways? Unless you are already on one and then only to the next junction.
can't tow if the towed car is SORN.
Towing rules these days are, the towed vehicle needs to be 100% road legal if any of its wheels are on the ground. ie, Taxed, MOT'd and Insured, and the towed vehicle (with any wheels on the ground) needs to show its own Number plate, the only exception is if the towed vechile is showing current Legal Licences Trade Plates but even then it still needs to be fully Insured and MOT'd.
You cannot use Trade Plates on any vehicle that is being Towed or Driven to a Pre or Un booked MOT, it must show the original Index Plates and be fully Insured.
Motorways, you cannot join a Motorway with a towed Vehicle (again any wheels on the ground) unless you are a Recognised Recovery Vehicle, you can recover a broken down vehicle (normally Van, truck etc, not car) to the next exit (as you say) again. any further you will need to be a Recognised Recovery.
