john guest fitting are push-fit connectors used in all kinds of trades i.e. plumbing, drinks machines, beer pumps etc. so yes, they are in B&Q, wicks & so but they are the bigger ones for plumbing. they are also known as JG-speedfit connectors. the ones most commonly used for WFP applications are the smaller ones used for the drinks industry.
do a google for john guest, then if you want to buy any get the part numbers from JG site & buy from
www.betavalve.com(or .co.uk, cant remember).
they are a superb fitting, just push on & pull off, no leaks or air intake. i use them on my facelift pole to plit the pipe.
tony