Shares in Jarvis, the rail maintenance group, jumped to their highest level in more than a year after the company reported an “extremely preliminary” takeover inquiry.

The stock, which has mostly languished below 20p since a profits warning in November 2007 wiped 75 per cent off its value, surged 30 per cent from 17½p to 23¾p after the company released a 52-word statement to the markets on the approach. It had leapt nearly 30 per cent the previous day.