The blue coloured line is the supply to the engine and the green lines are the supply to the engine. See my previous post. It may be counterintuitive but is a very common arrangement and not restricted to Morgan. Check valves do not feature and serve little purpose in this type of system as the flow of fuel is always considerably higher than the consumption of fuel by the engine. A simple pressure control valve in the filter canister restricts the flow of the returning fuel to the tank which is what regulates the pressure seen at the injectors.
The lines that you have coloured are metal tubes of which the two long ones are connected to rubber hoses at the engine.
