Barkers Advertising has won the 2m account to promote Midland Mainline trains.
The Birmingham-based agency won the business in a four-way pitch against Nottingham agencies Free style Advertising, Hudson Taylor Advertising and one other.
Barkers will use TV and press advertising to attract business users.
Midland Mainline claims it will spend 18m on new trains for the line, which will run from London to Derby and Nottingham.
The corporate livery and the design of the line, trains and staff uniforms was handled by Saatchi & Saatchi Design.
National Express, which owns Midland Mainline, this week won the franchise for Scotrail – the last major line to be awarded in the British Rail privatisation programme.
National Express now has four rail franchises. Additional lines are Gatwick Express and North London Railways.
The company has numerous coach services in Scotland and England and, as a result, is thought to have held detailed discussions with the Office of Fair Trading about its competitive position.
Last Friday the rail franchise director John O’Brien awarded the West Coast Main Line to Virgin. All 25 franchises are now in private hands.