Tedious fill-up continues (click...click...click)

I posted this in the RR forum before but thought I'd expand on it here in case it gets a wider audience or LR owners have had the same trouble.

My problem is that my RR classic is impossible to refuel quickly whatever angle the filler is held at.

Thoughts were of a blocked breather pipe...

I've been under the car and had the pipe-work apart, there is a big, unkinked fuel-input hose, and two apparent "breather" tubes off the top of it where it is metal just behind the filler cap. One fairly thick one runs to the tank and is clear.

The other - very thin - runs off somewhere inside the wheel arch (don't know where to). This, although kinked to fit onto the attachment just behind the filler cap, seems to be clear, but the angle of the hose and its diameter doesn't allow much throughput.

Any ideas what to try next?
(One thing to mention is that this was a 3.5 petrol car converted to a diesel by the previous owners I would assume with the original tank and pipes.)

Aside from this being mildly annoying but managable (I don't fill up everyday!), I'm doing a rally with 100+ cars into Africa in January and won't be popular taking towards an hour to fill up when we're all queued up for fuel in the only petrol station for miles around!!!!

I might be barking up the wrong tree, but aren't modern petrol filler necks a lot smaller than deeezil ones to stop people filling petrol cars with doozil. So wot diameter is you filler neck and do you get full penetration with the diesel nozzle?

Yep, its an old thing ('88) and the diesel pump gets right in. Has a problem even filling from a jerry can "fast" --- spews back up the filler pipe
Must be some kind of airlock

or a anti syphon device with some crap on top of it

My RR classic is the same, yet my previous RR classic was fine, only difference I can se is the newer RR has a wire mesh screen just inside the filler neck were the big hose fits to the tank to stop wazzoks siphoning yer white stuff, maybe this mesh is enough to restrict the flow of fuel from the pump.

I'll take the metal tube piece (filler cap to main rubber tube) out later and see if it is either full or crap around some antisyphon mechanism or can be "modified"
Not a nice job, lying under a car dealing with rusted jubilee clips, getting covered in underbody crud and diesel

Sorted
There is a mesh at the end of the metal filler pipe that runs down to the rubber connection which then goes to the tank.
This can be easily pulled out. Mine was covered in a jelly like "diesel snot" and there was also a leaf wedged above it.
Good advice guys --- thanks!

The rusted jubilee clips eventually freed, so a nice quick and easy fix - only cost me half a fingernail when pulling the metal tube out of the rubber pipe under the car...it came free with a whoosh

yer mean like i sed 2 days ago