Thank you for getting back. I will try out the mosaic dataset - not used this before as I have only done basic work in GIS. I did try to take each image into Gimp and clipped and recoloured it but when I put it back into GIS I was not able to open its properties to set the spatial reference - I got the message 'failed to open dataset'.
The colour of the tiles range from pale cream to pink and everything in between. I want to find a uniform colour so that it looks like a composite map when I reproduce it. I thought greyscale would be the simplest as otherwise I would have to alter each tile to get them to match up. I will try to attach a screen print of what a section of it currently looks like.