20,000 extra prison places will be five years late and £4.2bn over budget, spending watchdog finds

London’s Pentonville, one of Britain’s many ageing prisons - (Getty)

Government plans to expand the prison estate by 20,000 new cell spaces are running five years behind schedule and will cost £4.2bn more than first forecast, a damning report by the spending watchdog has found.

Even if the current expansion plans are achieved, watchdog the National Audit Office (NAO) predicts that there will still be a shortage of 12,400 places by 2027.