Blimey, you lot have been busy since my initial post
Im visiting the boat this weekend. Have a new 4" access hatch to fit to improve access to the tank connections, a new length of fuel hose to fit to the breather connection (that failed) and new stainless hose clamps.
I've got simple hand transfer pump and hose so will extract a litre or two and let stand in a bottle to see if theres any water in the fuel, while i replace hoses.
I have a water separator and filter fitted in the fuel system but want to check the fuel before i start pumping it through that.
I'm hoping theres not too big an issue, but will find out tomorrow. If all goes well, i need to get the engine serviced and winterised on sunday, - fingers crossed.