A widow's wish to hear her late husband's voice again has prompted London Underground to restore a 40-year-old recording of the subway's famous "mind the gap" announcement.

The subway system — better known as the Tube — said it has tracked down the voice recording by Oswald Lawrence after his widow, Margaret McCollum, wrote to ask for a copy of it when she noticed it was not broadcast in the system anymore.

McCollum said she used to frequently visit Embankment station to hear her husband's voice, but was disappointed when it wasn't there last year.

Nigel Holness, director of London Underground, said its staff has been so moved by McCollum's story that they dug up the recording and gave the widow a copy of the announcement on a CD for her to keep. Tube staff is also working to restore the announcement at the station, he added.

McCollum said Sunday she has been overwhelmed by the media attention to her story.

"I had no idea this was going to happen — I'm very touched by all the interest in it," she said.

The Tube's automated "mind the gap" messages, voiced by various actors, have accompanied countless London commuter journeys since the 1960s. Train drivers and staff made the warnings themselves before that.

London's subway, the world's first underground railway network, was begun in 1863. It is celebrating its 150th anniversary this year.