Well, a combination of "Twemlows Useful Parts Emporium" and Royal Mail meant that despite only starting this thread on Friday afternoon, the bits I needed arrived before midday today
I was a happy bunny - then i saw that the 2 fittings (each end of the filter) are actually different to each other - one has an 8mm tail, the other a 10mm one.
Luckily, with what i already had, plus Daves' envelope, there were enough bits to use, with one spare!
That plastic fuel pipe is a bit of a bugga to work with aint it?
Here's a tip for anyone needing to change their fuel filter - don't bother!
Seriously, with the fittings seizing up, it would be a good idea to douse them in penetrating oil a few days before starting.
Failing that, there is a foolproof way of doing it, which I eventually discovered
The trick is to realise that the access is limited anyway, and even worse if you have roll hoops -
start off by removing the access cover on the inboard side of the fuel tank area, under the tay in the hood (roof) stowage area.
Then releasing the filter from its clamp with a 10mm socket on a 1/4 drive ratchet.
This gives enough cleacence to move the actual filter fore and aft to get at the fittings.
With a 21mm (adjustable) open end spanner on the filter, and a 16mm on the fitting, loosten off the fittings slightly (beware of pressurised residual fuel - have a rag handy!) - in theory the outer (threaded) part of the fitting will rotate, with the inner bit staying still - Like on a brake pipe.
In reality, the 2 bits may be rusted solid (mine were, anyway) - hence as you unscrew the fitting, the plastic fuel line 'winds up' and squashes itself flat - weakening it and maybe giving it somewhere to split when under pressure
After a bit of head scratching, you may come to the decision that if you cut the pipe, you can refit the fittings later - if you think that - THINK AGAIN

They are a b@$tard to re-fit - there just isn't enough room to get at it properly.
Okay, here's what you do -
1) cut the plasic hose about 10mm from the fitting on the INLET side of the filter (rear of the car).
2) catch any fuel which runs out.
3) unscrew the filter from the front (outlet) fitting - leaving that fitting attached to the plastic pipe which runs forward to the engine.
4) remove the filter, with the rear fitting still attached, from the access hole - it will still have quite a bit of petrol in it so be careful. Drain it away carefully, then unscrew the fitting from the filter.
5) carefully cut the plastic pipe off the 8mm tail on the fitting, dont press too hard with the knife - you need to be able to re-seal it later!
You now have that sinking feeling when you realise that you can't get it all back together unless your hands are 3 cm wide and double-jointed - with the ability to excert vast amounts of longitudinal pressure on the pipe joint.
Okay, then, off we go again!
6) Remove the 4 screws which hold the cover plate on top of the fuel tank - it is the one with the wires going through it to the sender unit underneath. The screws are actually set screws (bolts) going into rubber scrivets. pull it to one side, feeding the wire through it as you go to give clearance.
7) by waggling the cut end of the plastic fuel line you will see the other end of it on top of the sender unit - carefully cut the plastic pipe on the spiggot on top of the tank - it is only plastic, so go careful with Mr Stanley!
8 ) pull the pipe out and chuck it away - it's (s)crap.
9) go and buy 60cm of rubber high-pressure injection fuel pipe (8mm bore) from your local motor factors - don't forget a couple of jubilee clips (size 000) - perhaps this should have been step 1????
10) fit the pipe to the fuel tank end and tighten up the jubilee clip - feed the pipe round the top of the tank and down to where the filter lives.
11) replace the 2 rubber 'o' rings on the fittings (Rover part) and screw the inlet fitting (the loose one!) onto the inlet side of the filter - tighten up with the same 2 spanners you took the old one off with.
12) screw the filter onto the outlet fitting - dangling somewhere next to the tank - and tighten up with spanners. Push it forward a bit to get to the rear fitting.
13) push the loose end of your nice new rubber hose onto the fitting - don't forget the jubilee clip. Do it up.
14) wiggle the new filter back into its locating bracket and replace the bolt.
15) turn on the ignition to pressurise the system - check for leaks.
16) if there aren't any, replace the cover plates.
It might sound a bit strange, but if you do it this way, and have the parts you need at hand - it is litterally a 10 minute job!
Shopping list:-
Fuel filter - Fram G3727
2 x 'O' rings - MG/Rover part # EDP9976
60cm 8mm bore Injection fuel hose
2 x jubilee clips (size 000).
Tools required:-
21mm open-end spanner (wrench)
16mm open-end spanner (wrench)
Cross-head screwdriver
10mm socket on 1/4" drive
Stanley knife
7mm socket for jubilee clips
I know this should be in the wiki, not on the forum, but I don't know how to do it
So please feel free to cut and paste it, or whatever else you magicians do!
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