Hi to anyone that can offer advice, and thanks in advance.

I'll start at the beginning.

About 6-8 weeks ago my engine began making a noticeably loud (how can I describe) whirring noise under moderate acceleration. It became louder the more power I put through. It's worth mentioning that, at this point, there was absolutely no noticeable difference in power. But I was concerned nonetheless, suspecting it to be a fuel pump or similar.

After 3 days, when trying to show this noise to my Dad, I over-revved the engine whilst stationary and the noise disappeared. Again, no difference in how it drove at all.

I spoke to the mechanic at my local garage, same garage for 9 years. He said i'd have to bring it down to be sure but it could be turbo, fuel pump etc. He was reluctant to diagnose anything until he'd seen it. But because of the times, couldn't book it in for over a week and this wasn't possible for me.

Fast forward 4 weeks, now we get an issue.
 

As I accelerate 'aggressively', in third gear at the time, I lose all power. The engine isn't off, though. There's just no power whatsoever but I can still steer etc. That is, until the car is at a crawling speed, then the engine cuts out. It doesn't stall. Perhaps this is when I put the clutch down? But once I switch off the engine and switch it back on again, there are no issues. 
 

Today I went for a drive (because what else is there to do) and I tried accelerating hard again. Sure enough, same again. I can put it in any gear and it staggers as the gear engages and then grinds to an inevitable halt. Engine off, engine on and as long as I accelerate slowly and i'm good.

 

If anyone can help, thanks again.

Does the glow plug lamp flash when the fault happens ? If so it could be an injector issue.

No, no lights come up on the dash at all. Then when the engine eventually stops, all the lights come on as normal.