In reply to a post by MJS1:

It finally appears this issue has been resolved so just posting an update in case anyone is in a similar predicament.

1 further Sky engineer and 2 OpenReach engineers did all their tests & could not diagnose any issues with their various tests.

However the last OpenReach engineer used some sort of amplification device in the immediate vicinity of the router & detected a strong disturbance signal around my satellite box (a Televes NevoSwitch device which my router had been sat on top of). The signal was strong even when the power was turned off which really surprised him.

He suggested to move my router away from this device & since doing that I have not had one internet drop in nearly 3 days. So still unaware of what exactly was causing the dropouts but have found a solution.

Thanks again for all help on this one,

~Yeah a faulty or poorly shielded power supply will do 'wonders' for RF noise. Wonder if the 1pm timing had anything to do with the timed recording of a program on a set-top then causing the Televes switching unit to wake up and draw some juice. Thereby causing your issue.

I knew I would be tempting fate by posting that this issue looked liked it had been solved, the connection went twice overnight.

REIN trained OpenReach engineer booked for Tuesday...