[grahamfromoldham]

I bought a '58' plate Astra 1.7d last year and it has developed a knocking noise which seems to be coming from the boot area (or somewhere at the rear). I cannot for the life of me find the damn thing that is causing it and I've eliminated the obvious...spare tyre, items in boot, parcel shelf. Has anyone else had a similar problem?
Oh, and it doesn't always happen when driving over a bump in the road, it occasionally happens when just bimbling down a straight road.

 

[The Apprentice]

Handbrake cables eventually slackening off from the outer casing or perhaps the shockers. Does it happen at any time during a long trip? Have you checked the hatch lock, it's not bouncing on the pin?

Possibly rear seat catches to lock the seat backs in position, I've noticed on mine that I think I've secured the seat backs firmly, but it takes more force than I thought.

How about a hibernating hedgehog thats trying to get out o:

 

[Scrooge]

try lubricating the boot latch and striker and the bump stops for the tailgate

 

[grahamfromoldham]

I can rule out the seat catches in the back-seats, but you've given me a couple of ideas...cheers guys