A "big change" in the quality of train carriages on the West Coast Main Line has been promised by a parent company of new operator Avanti West Coast.

First Rail managing director Steve Montgomery described the 56 Pendolinos it inherited from Virgin Trains as "tired".

He told the PA news agency that the former operator had "done a good job" but said the type of contracts it was given "restrict" investment into rail franchises.

Since 2012, the Department for Transport handed Virgin Trains a series of short-term deals which did not involve a bidding process.

Avanti West Coast - a joint venture by Aberdeen-based transport company FirstGroup and Italian firm Trenitalia - took over running services on the route on Sunday.

It is vowing to significantly improve the carriages used with a £117 million refurbishment of the Pendolinos and replacing Super Voyagers with new trains.

"I think that's really going to be the big change customers will see," Mr Montgomery said.

The revamped Pendolinos will have 25,000 new seats, more reliable wi-fi and improved catering.

The first overhaul of a train is expected to be completed by early autumn 2020, after which the others will follow "quite quickly", Mr Montgomery said.

Hitachi was awarded a £350 million contract on Friday to build 23 new 125mph intercity trains at its factory in Newton Aycliffe, County Durham.

The carriages will be longer than the Super Voyagers they are replacing and are expected to enter service from 2022.

The increase in capacity will enable Avanti West Coast to operate 263 more services per week, including doubling its frequency on the London-Liverpool route to two trains per hour.

"With the modelling that we've carried out, we believe Liverpool is a market that is underserved," Mr Montgomery said.

"If you've got a half-hour frequency, people are more inclined just to turn up and go. I think that's really important for that market."

Avanti West Coast will also launch direct London services from new destinations such as Llandudno, North Wales and Gobowen, Shropshire, while Motherwell, North Lanarkshire will become a major calling point.

Mr Montgomery said the new routes were carefully chosen for their passenger growth potential.

Other improvements planned by the operator include simplifying fares and ticketing, refreshing station waiting rooms, boosting accessibility and providing more car park spaces.

The partnership between FirstGroup and Trenitalia is also due to run initial HS2 services, although the high-speed rail project is in doubt and a decision on its future is expected after the General Election.