Thank’s Al
I used a combination of your primer and this one below for easier selection of copy and paste, thanks to Costas if your reading this.
Still a very long way to go but I now have a coloured image.
Trev.
Open all 3 images in Photoshop
Select the one with the red channel and duplicate it Call this Master. For the Master, go to the channels palette. Now all channels are the same so you need to replace the Green and Blue channel.
Open the Green image, and go to the channels palette - click on the green channel (they are all the same) CTRL A to select the image, CTRL C to copy it.
Now select the Master image, click on the green channel and then CTRL V to paste the green channel
Repeat with the blue image - but obviously using the blue channel
On the master image, click RGB in the channels palette and you should have a coloured image made up of the three