Should Classic RR Fuel Tank Feature A 'Flap'?

After replacing my original, Classic (B-reg) Range Rover's fuel tank, with a 'copy' make, petrol now
travels up the fuel filler neck, and leaks through the cap.
I've been told by the garage, that the tank should contain a 'flap' to stop this occurring, which this copy does not have.
However, I've enquired about some original tanks for sale, but the owners say they don't have the required 'flap'.
Are they visible from looking inside the tank nozzle, or perhaps just can't be seen?

Any advice very much appreciated.

Had the tank on my E-Reg replaced recently and had the same problem.

Neither the old or the new tank had a flap, and I get a strong smell of fuel when the tank is full, although, I understand this is common!!!

dont have a flap..thats why you cant find it..

replace the rubber on cap.and just under the top rim..

no flap required....

just a filler hose with good sealing (a new one not the old crap one with the rusty hose clips that came off the old tank) and a cap that has a working seal in it!

new ones are as cheap as chips from local motors factors or flebay

In agreeing with the advice you've been given I've never heard of any such 'flap' myself. All Classics tended to suffer from this complaint until LR extended the filler neck in '90/'91 twenty years from the RR's launch date! My previous '89 & present '87 could/can be filled to the service station's pump 'cut-off' point, even in summer, without leakage or smell though I do take the precaution of not parking the car facing uphill or leaning to the driver's side. My partner's '85 that she owned several years ago did however suffer from the spillage you describe, even when parked with a (nearly) full tank on level ground :doh: