had chat today with garage, think they haven't been able to book the electrician in yet, anyway, today it failed to start which is what we want so the sparky can check it out while the fault is there, car is outside in garage compound. Seems the PCM is that large metal box low down between cais/battery/water bottle area, they need to be cool hence on outside of car and also subject to weather there too. In order to access these they have to be split in two halves and this where weather could access the pcm and cause problems if not sealed back well or from factory, so it's an outside possibility of ingress causing software/hardware fail.
Yes Dave it is possible for Mountune to see if there is a software/mapping fault and they could tell also if it is an actual hardware/board failure, not sure if the electrician can tell this, so if software it is possibly fixable. Electrician is booked for tuesday.

If he's any good he should be able to tell it. Guess you've got to just wait and see what the autoelectrician says before pursuing Maps from MT

update - electrician has had a good look at it (ex TVR guy) done a few tests here and there, does come up with a processor fault so pretty much confirms PCM bit wonky.
PCM ordered should be here tuesday, Stage 1 and 2 will be updated by Ford onto PCM, hopefully car will start so that will be a good test. Awaiting to hear from MT to see if car can be driven locally for a few weeks as a test using stage 2 on the Stage 3 engine mods. I know it can be driven as one was driven to Mountune with the inlet for Stage 3 already on. So my options are to test it or just low load it straight to Essex when the PCM and Stage 2 are on.
Looking like £2,000 best part of this will be.
This is quite rare, am aware of one RS PCM failure. In order to apply Stage 3, PCM is split open, so if not resealed or anything gets in could be the cause, will never know.

Ouch not good mate

update, Ford are not keen to go down PCM root, not convinced. Electrian still has car and has been testing and monitoring it, seems the battery suffered a small voltage drop (it's a new battery from few weeks back when problem first occurred), he charged it up and the car starts fine and still starts now. Something is drawing a few extra volts, could be starter motor although fires up strong, alternator has been checked for output too, starter could be old and bit tighter. I suggested only thing same is left overnight and it won't start, three times now, so only change is that my car is alarmed and locked, could my Clifford be draining over time, guy who fitted it said no, drains less than a clock in car he immediately then said have you got correct battery on, I said hope so, he said if alternator is a smart charge one, very likely then the battery must be a Silver Calcium NOT a lead acid which will not work properly.
I've asked garage to check they said will do ?

Seems a strange one mate,odd they don't want to change the pcm

So your PCM has been cracked open, hence the suspected failure from water ingress?

Yes Only way Mountune can apply updates for high end tuning ie MR200, all tuners that make major updates do open PCM up. So, yes it is possible and then again just a glitch none related to ingress or updates. PCM is split open, then contacts on the board are made for updating.
(minor updates 165/185 are done v Ford ETIS)

update

I'm about to call a local breakers and obtain a PCM cheap to try out, we will update with 165/185 and then test the car. This morning it did not start after starting yesterday after battery charge, it was left overnight this time with alarm on but no voltage drop today. Alarm guy who fitted my Clifford 5.1 says any drain is less than a clock so highly unlikely alarm. If can rule out PCM then may have to look at Starter and Alternator replacement. Battery confirmed as correct one one.

Local Breakers have some £80 need to call him back tommorrow to arrange deliver.

thanks to Dan, also going to check the interior boot light is not staying on, I did swap it out for a led version and that was not so long ago and before all this, already texted my service manager to check it and he said will do. Definitely one occasion I did the morrisons run at night and would have opended tailgate several times and in morning car did not start up. Worth checking out.

used engine management box arrived at garage today, £100 delivered, data copying time now.

and the saga continues:-

Ford can't do the updates as their computer no longer supports XP.
Car and used engine management box now all going to be shipped to Mountune next week.

What a bloody nightmare this is

don't know what's going to happen, costs after shipping to MT are now £800 on parts bought and transporter.

starting to think scrap the car..................