The two firms have been named principal contractors on the Multi-Asset Framework Agreement, which  will cover upgrading and building platforms, bridges, crossings and signal boxes, as well as electrifying railways.

The deal, which is due to come into force on 18 August, is a coup for Spencer Rail CEO David McLoughlin, who joined the firm from Network Rail Infrastructure where he was finance director this month.

Balfour Beatty Rail held the previous MAFA framework for Scotland, which came up for renewal.

A more clearly defined scope of works will be agreed once the £150m framework contract is in place.

Each MAFA commission could cover design, surveys and early contractor involvement in connection with the works, including assisting Network Rail in developing schemes from inception early in the GRIP life-cycle right through to delivery.

Spencer is also delivering projects on a revised MAFA framework in East Anglia and Kent.

The £100m turnover Spencer Group employs 450 staff altogether, including 300 in its rail division.