Complex sentence: The West Highland Railway started to look for another contractor, but after agreeing an increase of £10,000 Lucas & Aird resumed work in October, although it would be spring 1892 before the workforce returned to its full complement.
Split into simpler sentences: The West Highland Railway started to look for another contractor, but by October the parties had agreed to raise the price by £10,000, and Lucas & Aird started work again. However, it would be spring 1892 before the workforce returned to its full complement.