This photo restoration involved removing the marks & discolouration, applying a black & white conversion to remove the colour-cast, then finally adding appropriate colours to match the era it was taken, (this part is often guesswork). There are further photo restoration examples here.

Scroll down to view the following images:
Image 1) Original.
Image 2) Restored.
Image 3) Restored with 8 x 10 border.
Image 4) Restored with 8 x 10 border and coloured.

Photograph restorer in Newport, South Wales: Information & prices.