catweazle - fraudulent claimants are now prosecuted for contempt of court etc. i think there is also recent case law making them pay back compensation awarded in connection with their fraud. not before time! with respect to the op - if mil makes a claim, she wont get much if she has an extensive medical history - probably a few months discomfort at best if she can convince the medical expert. the experts have certain tests which weed out fakers anyway - so if she tried to exaggerate her symptoms they would almost certainly pick up on that as well.
chukky - was the form your dh completed for his solicitors or insurers? if the former, then on receipt of that the solicitors probably sent a letter of claim to the other driver's insurers - they would have put any other losses in that (vehicle damage, car hire, excess etc) including him having banged his head. the insurers have a minimum of 3 months to respond, which is probably why you've only heard something about it now. as to why the solicitors pursued the claim, i expect they only sent the initial letter before they got a call from your dh saying he didnt want to pursue it. most lawyers wouldnt close a file however without something in writing (because otherwise you get clients all the time saying i never said xyz in a phonecall so we always insist on written confirmation of all important matters!)
as georgi said the other driver's insurance company would rather offer £250 now than risk your dh actually having an injury of more than a couple of days duration (which they couldnt possibly know one way or the other without waiting for a medical report) becuase if he did have an injury worth £1000 or more, they would then have to pay his solicitors fees (on a fixed scale) and the cost of the report etc.
its in the insurers interest to make an early pre-med(ical report) offer to buy off the claim. its not just claimants who can be dodgy though - there are a couple of big motor insurers who do their best to bully people into settling potentially quite serious claims by telling them they will have to pay their solicitors costs (not in 99% of cases they wont), that they will have to attend medical examination/court in london - this is used a lot for elderly clients in rural areas, that they wont get any money for years & will get into debt (not entirely true either )
sorry - bit of an essay