A slice of Birmingham’s history revealed by workmen on the city centre Metro extension will be covered back up, public transport bosses have confirmed.

A Victorian shop sign, hidden for years under modern branding for the Waterstones book store in the former Midland Bank headquarters on New Street, was exposed during building work on the £120 million tram line linking New Street and Snow Hill stations.

The sign has been the talk of amateur photographers and history enthusiasts keen to know more about it.

The rear entrance to the Grade II listed book store is being reshaped to create room for trams to turn the sharp corner of Stephenson Street while still allowing space for commuters using the rebuilt New Street Station.

Construction work revealed a hand-crafted sign, painted on wood, which reads ‘& SON RAILWAY AND STEAMSHIP PASSENGER AGENTS’ in a serif typeface befitting the era it was made. The name of the travel agency running the shipping services cannot be seen.

Leading Birmingham historian Professor Carl Chinn said he had been approached by several people keen to find out more about the travel company once based there.

Prof Chinn consulted a Birmingham edition of Kelly’s Directory for 1908. Kelly’s was a guide to all businesses and tradespeople in UK towns and cities.

The guide, a forerunner to today’s Yellow Pages, lists several shipping agents based in Birmingham city centre, but none are listed on Stephenson Street.

An 1881 trade directory in storage at the Library of Birmingham archives department lists Thomas Cook & Son being based at the building, while in 1900 a Gaze & Son, tourist agent, is listed there.

Prof Chinn said: “This intriguing sign connects us to a world of steam; a world that owed so much to the engines of Boulton and Watt made at the Soho Foundry. It also shows how the world was being opened up to wealthy travellers.”

A spokesman for Centro, the region’s public transport body overseeing the Metro extension, said the sign had been discussed with Hortons' Estates, which owns the building, and tenant Waterstones.

“Owing to cost and time constraints in getting the shop frontage ready in time for the Christmas period it has been decided that its removal will not be part of this project,” he said.

“The sign is old and quite fragile and to remove it properly would mean a delay in restoring the frontage for Waterstones. However its discovery has provided a fascinating glimpse into the building’s past and, while it will be covered up again, we now know it is there and it can be preserved for future generations.”