Winseer:
Lots of special stuff to read through here. Special thanks to Thecouch’s input 
I have not attended an ID parade, so do not know if the registered keeper of the vehicle was the one driving it, indeed the owner could have been the even-more-■■■■■■ passenger who’s got his mate to drive - without insurance would that be?
Their car was more damaged than mine, but as far as I know has NOT been written off unlike mine, since it has a value of 5 figures apparently…
I know where this guy lives from the police, but don’t feel it appropriate to make contact with them.
After the original collision, the driver offered me money to “let it go” and not involve the police…
Alas, I’d already called the police so temptation to possibly do an illegal thing was averted you might say…
On realising that I wasn’t going to play except “by the book”, he suprised me by managing to start his mangled car, and drove off…
When the police turned up, the entire front number plate was on the road - so there was no mistaking the formal identity of the vehicle that hit me.
The other party insurer isn’t so much “refusing to deal with my claim” - they are just placing what I see as unreasonable obstacles in my path…
(1) Expecting me to sign some kind of indemnity form, which from what’s on it, leaves me totally at their mercy, should they then decide to refute everything.
(2) Asking for my “agency’s accounts going back months”, so they can work out “how much has been lost out of pocket” officially. This doesn’t seem reasonable, as the money I’ve lost is what I’ve drawn down as holiday over the two weeks loss of earnings I’ll be paying for. I consider request for anything outside the two week period to be totally irrelevant, hard to get, upsetting to others to get, and bang out of order to even ask me for. 
MY insurer reckons they are correct to ask me for all this “proof”. So much for “bang to rights open and shut case”! 
The amount of effort required to get all this means I might as well get it for a court proceeding, and use it in full.
My insurer says that “I will get my full no claims re-instated once this is all signed off”. Some have told me that this is ■■■■■■■■, and my premiums will stay high for some time to come, even if they are knocked down a bit from the max they seem to be at now (tripled from last year’s premium) If this advice is correct, it would mean my own insurer is lying to me, and I’ll need to add to my claim from the other side the difference over the time it takes to re-gain full no claims multiplied by the amount per year difference in premiums. Already my insurer has said "Because insurance premiums are “up this year”, that “isn’t going to happen”. 
Nothing short of a full re-instatement of a maxed no claims bonus premium will do. Who do I claim this from then?
What do I claim and how do I “prove” all my wasted time, effort, energy, and stress in all this? Would a medical stating “elevated blood pressure” and other deterioations in health signed by my GP do, or do they want me to report to ATOS or some other quack who’ll declare me “nothing doing here” even if I’m missing body parts?
Why have they not made me any kind of quick (albeit low) cash offer with this expectation that I’m going to be keen to quickly sign it all off? Is their money on me being born yesterday - or the early hours of this morning FFS!
I’ll indeed give MIB a call over what seems to be skirting around the law to try and get me off their back. My own insurer is keen for me to sign off as quick as, because me not doing so pushes back THEIR claim for their own expenses already paid out - namely the market value of my vehicle, which I have already received at least.
There should be no requirement to legally pursue the other driver direct, because chances are, he hasn’t a pot to ■■■■ in to cover his own legal bill - and neither do I come to that.
I’ll sue the ones with the money that can afford to pay up. It’s just getting them to see reason, and live up to their legal obligations that’s my problem here I think.
Asking me for difficult to get “Proof” like third party accounts (I work for my agency - I don’t own it!) seems like just another attempt to push me off the pot…
My own insurers have refused to take my out of pocket expenses claim further until I send them the requested accounts. I’ll hand them over to the court officials - if I eventually jump through the hoops of getting it all!
What result do I want?
(1) An offer of cash in full and final settlement as soon as possible. If I have to make them pay, it’ll be in court. There’s no in-between… Once I get a court date, I am beyond being “paid off” for any amount less than the total cost of what they save by not going to court. This means mid 5 figures I reckon. Once in court, they can flaff about as much as they like, since every day wasted from then on pushes THEIR costs up - providing I can get “no win no fee” representation. 
Thanks to Mike C as I missed that the DD has been dropped and they looking at leaving the scene of an accident which will have caused the Insurers current stance.
The situation is that the RTA under section 151 2b) makes an Insurer liable to claims by persons not insured by the policy eg car thieves, friends who have borrowed your car (And don’t have their own cover) etc. The legislation refers to obtaining judgement against such persons to invoke this part of the RTA to make an Insurer liable. The reality is that the driver just needs to be “identified” eg the police arrest a car thief or the “friend” who borrowed it gives their name to the injured party etc for the Insurer to be liable under RTA section 151 2b)
I assume the third parties Insurer is working on the basis that if the court case fails then the driver of the car will not have been identified meaning they’re not liable under RTA 151 2b) and also not liable to pay the OP’s costs. If this is the case the OP would generally look to the MIB although they will normally pass it back to the issuer or any motor Insurance Certificate current at the time of the accident eg the third parties Insurers to handle and pay the claim as the MIB is really there for the genuinely uninsured / untraced.
Hence my advice to contact the MIB for a chat and some advice still stands, bear in mind your situation will not be unique and they will have dealt with similar situations in the past so will be able to advise you how it will normally pan out and what they will expect of the Insurer.
Bear in mind that the court dealing with the leaving the scene of an accident will be working on the basis of “beyond reasonable doubt” when judging whether or not he’s guilty or innocent. However if you or your solicitor issue proceedings against him the court that deals with that works on the basis of “The balance of probabilities” which in effect is the judge looks at the evidence and weighs that up with how he views the witnesses testimonies. It’s perfectly possible for the criminal court to find him not guilty of leaving the scene but for a county court to find him liable for your costs. Should you obtain such a judgement then his Insurer then comes back into play due to section 151 2b). They may not even let it go to court if they feel they will lose as it means they rack up court costs they can avoid by settling before court.
