FTSE quarterly review confirms raft of changes to 100 and 250 indices

Smurfit Kappa, Ascential, Countryside Properties and Hill & Smith were also promoted to the mid-cap index, where along with the other newcomers will be officially added by FTSE Russell on 20 June.

As indicated recently, Inmarsat rejoins the mid-cap index after just a year as its shares were hit when the satellite group cut its full-year revenue guidance by $50m amid an ongoing recession in global maritime and energy markets.

Demoted from the 250 were Lookers, Melrose Industries, Northgate, Ophir Energy, Interserve, Jimmy Choo and the Highbridge Multi-Strategy Fund.

CYBG is the holding company that owns Clydesdale Bank and Yorkshire Bank consumer lending brands, which was floated by National Australia Bank in February. Its shares have surged from their 180p float price, where it had a market capitalisation of £1.58bn, to 275p.

Joining in the same month but with a debut valuation of less than half that was CMC Markets, the spreadbetting firm founded by Peter Cruddas in 1989, it has gained ground at a slower rate, rising from an initial 240p to above 270p recently.

Metro Bank is a more recently formed challenger bank that had its initial public offer at a price of 2,000p in March after being founded by US businessman Vernon Hill in 2010. It has since risen to 2,241p where it has a capitalisation of £1.8bn.

Irish based paper-packaging company Smurfit Kappa was added after changing to a dual listing, with London now its primary listing and Dublin secondary.

Another February flotation, Countryside Properties is a housebuilder with high growth aspirations and market leading position in public-sector housing redevelopment. Since listing at a price of 225p and a market cap of £1.01bn, the shares were hiked up above 275p by encouraging interim results in May.

Ascential, the publisher formerly known as Emap and Top Right, had 35% of its equity floated in February by private equity firm Apax and Guardian Media at a price of 200p that gave the group an £0.8bn valuation. The shares have since risen to 238p.

Hill & Smith Holdings, an infrastructure product and galvanising services provider, has the longest stock market history, having floated in 1969. After an uninspiring decade, since the millennium the shares have surged from around 60p to around 925p, including a leap from just over 400p in the last three years.

As indicated by the comments from some, all the companies should expect to see benefits for shareholders and attract new institutional and retail investors.

"Inclusion in the FTSE 250 Index is another significant milestone for us all at CMC and we look forward to widening our existing strong investor base with new shareholders," said CMC founder and chief executive Peter Cruddas.

Smurfit CEO Tony Smurfit said: "We expect our inclusion in the FTSE AllShare to provide an incremental benefit to our shareholders. Over time, our new dual listing arrangement should widen the base of investors eligible to invest in the group while further strengthening the liquidity in our shares."