Work has started on the final stage of East Midlands Trains' £30m programme to completely refurbish all of its trains.
The work, being carried out at the company's Derby Etches Park Depot, involves improving train interiors and increasing available luggage space.
The firm's 27 Meridian trains are undergoing a £6m refurbishment due to be completed by early 2012.
Managing director for East Midlands Trains, Tim Shoveller, said he hoped passengers would notice the difference.
He said: "Whilst the Meridians are the newest trains within our fleet, we still want to make sure they given their fair share of care and attention as part of our refurbishment programme.
"We're sure that our passengers will be delighted with the extra touches, including the additional luggage space and the new luxury leather seats which will help to give an extra special feel to our First Class coaches."
The Meridian trains (Class 222s) travel on the East Midlands Trains' mainline route to London, which includes services from Sheffield, Derby, Nottingham and Leicester to London St Pancras and the daily service from Lincoln to London.
East Midlands Trains recently completed the £10m refurbishment of its Class 158 trains, mainly used on the Liverpool-Norwich route and the £9m refurbishment of its HSTs used on the main line to London.
The 28 Class 153/156 trains, used for local services, were currently being refurbished, the company said.