So one of my tickets after sending away unsigned, they have sent a new BLANK S172, this obviously has an updated date on it,...
In my view you should not respond to this second request. Instead you should concentrate on establishing whether a response to the first request was received by the police. If it was not, I would respond to that one and not this latest one.
There is (coincidentally) a Scottish precedent where the police served a written s172 notice on a driver which, despite a reminder letter, did not receive a response. About seven weeks after the issue of the first s172 request, The police then visited the driver at his home address and asked him who was driving the car at the relevant time. He replied "I have no recollection of the correspondence. I have no idea who was driving at the relevant time and date as my wife and I both drive the car."
He was eventually prosecuted under s172. The proceedings began after the six month time limit based on the service of the first (written) s172 request but before six months limit based on the second (verbal) request. The stipendiary magistrate ruled that proceedings were time barred, basing that decision on the date of the first request.
The Procurator Fiscal appealed that decision in Scotland's Appeal Court, on the basis that the six month period to prosecute began 28 days after the second (verbal) request was made. The Court ruled against the PF, saying that if the date of the second request were to be considered, it has the effect of providing the police with an open ended period in which to prosecute simply by making multiple requests:
https://www.scotcourts.gov.uk/search-judgments/judgment?id=77be8aa6-8980-69d2-b500-ff0000d74aa7This has a significance for you with your strategy of going "unsigned". The police may attempt to begin proceedings based on this second s172 request (or any subsequent requests they decide to issue) and so prolong the period during which you have to "keep your head down".
