I'm not familiar with this area - although I know more about it than I did before I looked at the links on this thread. The official designation is total mess. I've played about with streetview and I think this is the 2008 view of your pelican,
https://www.google.com/maps/@51.4930224 ... 312!8i6656
Magnified here to show the "END OF ROUTE" sign in the distance.
https://www.google.com/maps/@51.4930224 ... 312!8i6656
It looks as though that sign has gone and with it what was a rather vague cycle route across the footway. Within the limits of streetview, once a rider has gained the footway, there's now nothing official that I can see marking the limits of any cycle route.
When deciding your next steps, the watershed is the point when you decide if you are prepared to go to court to contest this.
I've only ever had one fixed penalty - so long ago that it was when yellow line parking was a police (traffic warden) responsibility, enforced through the courts. My car had an intermittent fault and when a (proper) garage was trying to diagnose it, it broke down on double yellows and was ticketed. I paid the penalty to the Magistrates' Court but wrote to the police with all the evidence that it had been in the garage for repair for the intermittent fault. In due course, I received a refund from the Mags' Clerk, followed by my garage invoices etc from the police. Something like that might work.
Otherwise, I think it might be risky - in cash terms - to decline the ticket and go to court. I think that if you were legally represented the CPS would run rather than make a stand but I'm not confident of that.
One key bit of information here is whether your ticket was issued as the result of an edict. It's apparent from this thread that a lot of riders are using this bit of footway and there are two ends to that spyglass: does it mean more enforcement is necessary or that a lot of "otherwise law-abiding" riders have been left confused?
FWIW, a key point for the prosecution to prove in the Highways Act offence is "wilfully." When the legislation was passed, I think that was to protect eg horse riders who horse bolted, but it might be arguable here that genuine confusion meant your actions were not "wilful.". NB, I don't know: it may well have been decided one way or the other at court already. If you have deep pockets and would like a reported case with your name in lights eg DPP v UKcyclistnewby you could give it a run through the higher courts.
https://www.legislation.gov.uk/ukpga/Wi ... section/72