Porterbrook is one of the three major rolling stock operating companies (ROSCO) in the United Kingdom (the other two being Angel Trains and Eversholt Rail Group). It owns around a third of passenger railway locomotives, multiple units and coaching stock running on Network Rail's system which it leases to various train operators.Since 1996 Porterbrook has spent more than £1.5bn on new rolling stock in the UK and also leases to freight companies Freightliner, GB Railfreight and DB Schenker.