Thanks Eric,
Now looked at loads of images, sites and perhaps what I am looking for does not exist. Imagine combining a Busbar with a relay block so you have a common rail for all the +ve feeds on Pin 30, rather than have individual wires. Seems there are combined Busbar fuse blocks but not relay. Don't beat me up too much on the sketch, but this is what I think would be an elegant solution. i.e. the socket for each relay is already connected to a 12v rail without the need to run a wire outside the box to a busbar / eyelet on the battery . .
Does such a think exist, or am I missing something?
Fused relays fed from via a common supply with a (high capacity) in-line fuse is probably as close as you could get but not as elegant as what you're thinking of. I had a look through the vehicle wring product catalogue and what you're after doesn't appear to be for sale.