"Knock for Knock" has not existed for about 20 years

"Knock for Knock" is entirely different to split liability eg 50 / 50.

Knock for knock was an agreement between participating Insurers whereby they agreed to not pursue each other for accidents between their customers irrespective of blame. So in effect the Insurers paid their own customers own damage claims (Assuming they were comprehensively covered)

The idea of "Knock for knock" was to save particpating Insurers on the admin of chasing each other for money.

A customer would prove they were not at fault in an accident by recovering their excess from the other Insurer which would then mean their no claims bonus was unaffected and the claim was marked as non fault.

Knock for Knock ended about twenty years ago as some Insurers who specialised in young drivers eg Pegasus realised that they could build a business model around knock for knock. They changed their pricing to attract solely third party only of TPF&T customers with no comprehensive customers. By being members of the Knock for Knock agreement it meant that if one of Pegasus's young drivers who was TPF&T covered had an accident with a Norwich Union (Now called Aviva) customer who was comprehensively covered (as were the vast majority of NU's customers) with the accident being the Pegasus client. So Pegasus would pay their own customers own damages which were covered by the policy which would be zero and NU would pay their customers own costs. Because of the knock for knock agreement NU would not pursue Pegasus for their costs.

So Insurers whose customer base was predominantly TPF&T & TPO eg an Insurer who specialised in young drivers were being subsidised by Insurers such as NU whose client base was virtually all comprehensively covered. Hence the end of the knock for knock agreement and also one of the reasons young drivers Insurance is considerably more now days than it was back in the 80's & 90's when the knock for knock agreement kept the prices down.

Split Liability which is what you actually mean and is used where an accident is caused equally by each party also known as 50/50. This is also used on accidents such as roundabout claims where it's difficult to work out who was at fault especially as each party has a tendancy to give a different story and blame the other party.

With a 50/50 each Insurer would recover half of their outlay from the other party with the clients also recovering half of their uninsured losses from the other Insurer.

They're entirely different things, one basically being an accounting excercise to try and save on admin costs, the other being a way of apportioning blame especially in an incident where it's difficult to work out definatively who was to blame

Similar thing happened to me about 20 years ago, I was the one backing out and I was held 100% to blame and in retrospect I was. The arguement was that if I had seen the other car in motion it would have been obvious to me what path it was taking ie. into the adjacent bay. Whereas the other driver saw what was to all intents and purpose a stationary vehicle and couldnt reasonably expect me to suddenly move into his path.

There is really no getting out of it. Ask the driver backing out if he saw your neighbour, if he says `no` its an admission that he didnt look properly, if he says `yes`, you can say "so do you make a habit out of backing into other cars then?"