Looks like you did a really good job. I know this is difficult. About 5 years ago, I decided to re color a picture that was partially destroyed. It took me a long time as I had no idea of how to do things and was new to Gimp. I hunted through a lot of tuts on the internet and had a few rough beginnings but I finally got it done. Wish I knew then what I know now. Would have made it a lot better and certainly a lot easier. I might just try that pic again and see if I can do a better job!

Sallyanne - just want to echo what Warrior said

Thank you Warrior, Pat & OMG.

Pat, now that you know your way around gimp better I am sure you can

Thank you for your confidence in me, Sallyanne! If I do it, I will let you know!

Wow that is a quite Beautiful Picture.

Hi Sallyanne, thanks for the link to the tutorial.

I had to check and actually this technique facilitates a lot, and it speeds up the coloring of the images.
Below my attempt following the tutorial (Of course I need more practice ).

PS. I think the technique described in David's tutorial shows better results, but it's always good to be able to choose which technique to use.

That is a really nice job.

I recently wished to colour a photograph and realized that I no longer had a copy of my own tutorial! So I came here, only to find that the PDF file was incomplete. Fortunately I was able to find the document on Gimp Learn.

I have updated the file at the start of this thread. Apologies for my error.

An additional note:
The tutorial used overlay blending mode for the colour layers which, at the time, was the same as soft-light. The two are now different and I find that soft-light generally gives better results. The tutorial has been changed to reflect this.