Train operator GNER has signed a £30m contract to completely transform more than 300 of its electric coaches.

The contract, believed to be the biggest of its kind in the UK, will see a re-design and re-fit aimed at boosting comfort for the passenger.

East Coast Mainline operator GNER has already announced a £100m package of improvements after winning a two year extension to its franchise.

Work on the interiors of the Mark 4 coaches in the company's electric 225 fleet, built in the late 1980s, is expected to begin almost immediately.

London based design agency James Park Associates, which has been involved in a number of luxury transport projects including the Venice Simplon Orient Express, has been signed up for its expertise in the field.

It will be supported in the project - codenamed Mallard after the world famous train - by Design Acumen, responsible for award winning designs such as the British Airways "Bed in the Sky".

Train leasing firm HSBC Rail is another partner in the project.

The agencies involved will report to GNER's head of design Neal Stone who will lead a 12 strong team on the project.

They will be looking at features such as seating, lighting and carriage layout.

The refit, which will be carried out on a rolling basis, will last about 18 months with the first coaches coming on stream from early next year.

GNER spokesman David Mallender said: "Modern designs mean that you don't have to take up so much space to fulfill the same job.

"Coaches will be completely stripped out and work will start from scratch to the standard of brand new trains.

"This is a very big project for us and we are very excited about it."

GNER has been carrying out market research and taking input from its staff working in departments such as engineering and catering to see what is best required.

The company has already tackled a fault with the air conditioning inherent in the design of the electric 225 fleet by bringing in a team of Australian specialists three years ago to correct the problem.