In line fuel filter, recommendations

... a filter in the tap which should keep most of the rubbish out. Unfortunately this means removing the tap (hence draining the tank) to clean it. I have used one of these with good effect on a non-Norton:

https://www.classicbikeshop.co.uk/in-line-chrome-fuel-filter.html

Sounds like time to replace petrol pipes. Ethanol proof rubber lines recommended.
The old ones don't like modern "petrol". All fuel lines does become hard with age.
Plastic pipes get hard faster. Find easily bending rubber tubes. Many modern ones are stiffer because they are designed for the higher pressure from fuel pumps and have bigger outside diameter.
The cheap plastic transparent filters works for me. You can see amount of debris. But there are metal filters too, some with transparent middle.
Yesterday bought very small plastic ones intended for lawn movers for a two stroke racer where short total length was needed.
 

Mark, have a look at Apico petrol pipe and fuel filter. The pipe has lasted well on my bikes and they do metal bodied fuel filters. 

I think  ian_soady

Is right I have had them on My Triumph for a few years and never had a problem with them, when need to clean just take them off unscrew clean and put back.

Cheers Mo

which is very flexible and doesn't seem to be damaged by modern fuels.

https://www.carbuilder.com/products/low-pressure-fuel-vent-drain-hose-6mm-2?_pos=1&_sid=fc263323a&_ss=r

Having perused the link above I would be asking the seller if the hose will withstand petrol continuously rather than as the heading says suitable as a "vent and drain" hose.

Hose marked SAEJ30R9 is supposed to be proof against E10 petrol.

Mark, I had the original Norton supplied clear plastic in-line fuel filter in my Commander.
Then ethanol arrived. 
The bores of the inlet and outlet reduced. The inlet and outlet pipes were no longer aligned. 
Bike started to run weak on high throttle. 
And then the pipe 90% fell off the filter output, dropping a large proportion of the fuel tank contents over my right leg and the very hot exhaust system. The engine still coughing along. Stopped in a lay-bye because fuel gauge dropping rapidly.

I consider that one of my 9 lives. 

The plastic had become soft with the ethanol. The tight pipe clips had squished the connectors and were no longer tight. The bores of the connectors were about half their original size. 

I only trust metal bodied filters now. 

Peter