R52 turns over but won’t start...!

I'm hoping someone can help with this particularly annoying problem...
A few weeks ago, my wife drove home from work, parked on the drive and locked the car up. No problem. A few days later, went out to it, tried to start it and ran the battery down as it just refused to fire and she refused to give up trying until the battery gave up first.
A friend brought up a diagnostic laptop and the only (relevant) fault code was P1692 which appeared to point towards a throttle body problem; the friend decided it probably wasn't that and we explored other options.
I pulled a spark plug and turned it over - no spark.
I checked the fuel and none was being pumped to the engine.
Also, when turning on the ignition, I noticed there wasn't the usual sound of the fuel pump initialising...
Firstly, on advice, I changed the crank position sensor - no change.
I checked all of the fuses in the engine bay box and the cockpit panel - all ok (including the 40, 50 and 100 metal ones underneath the engine bay box).
I removed the fuel pump and tested that and it was fine, although checking the wiring in the multi-plug showed no feed was getting to it. The relay was soldered onto the inner fuse box, so I replaced the whole thing.
Still nothing.
I took the bull by the horns and replaced the throttle body, thinking that as the P1692 specifically mentioned that, it may be at the root of the problem...
Still nothing.
So here I am, a bunch of replacements made and no further forward. The same error code is brought up through the ODBII connector and nothing I've done has made the slightest difference...
HELP!!!!!!