Thank you

I m running a vapour speedo if it's wired to the blue wire does it only illuminate when the lights are on ?

Yes

I m running a vapour speedo if it's wired to the blue wire does it only illuminate when the lights are on ?
Think I might wire it to brown wire so it will light up when ignition is on

First bit should be Light Brown from the switches to Yellow/Red from the loom.

OK Dan you should have
As follows

Yellow/Red from switches to Red/Yellow from loom behind the headlight, its power from the lighting coil via the regulator/rectifier.

Blue from switches to the blue in the loom, its power for clock lights that come on with your lights. Goes into loom and straight back out as a double blue female connector one goes to speedo one to rev counter.

Pink goes direct into pink in loom the direct to the horn.

Black is a common earth and can go to any spare black coming from the main part of the loom.

Dark Green is left side indicator power and indicator light in rev counter.

Dark Brown same as above right side.

Brown/White is power from flasher unit, goes direct to flasher unit.

Yellow goes direct to headlight bulb high beam with a split connector that powers high beam light in rev counter.

Green goes direct to headlight bulb normal beam