This month marks the 30th anniversary of the launch of the Thameslink line services through central London. The first trains ran on the 16th May 1988, but the launch was marred by cancellations after a train developed a fault.

That was not a good start for a line that provides a now vital north-south link through the centre of London, and it’s almost unimaginable that such a service was once thought of as a bit of a daft idea.

Like a lot of railway upgrades in London over the past few decades, it was the reuse of Victorian infrastructure that permitted the new line to come into existence.

The core of the Thameslink service is the Snow Hill tunnel, opened in January 1866 to create a north-south link for passengers, and at the time more importantly, cargo. The tunnel runs directly under Smithfield meat market, and the railway was an important supplier to the market.

There were three stations on the new line, at Snow Hill, Ludgate Hill, and much larger, at Holborn Viaduct. In 1916 though, passenger services ceased through the tunnel while Snow Hill station closed. Ludgate Hill station, which is very close to Holborn Viaduct station closed a decade later.

Cargo carried on until the 1960s, until eventually the tunnel closed entirely. The tracks were lifted, and it seemed that the tunnels were to remain an unused asset until they were slowly chopped up by office blocks being built on top of them.

In the intervening years, Holborn Viaduct operated as the city terminus station for trains coming up from South London via Blackfriars.

Although services to Holborn Viaduct started to decline after the war, the station was still in use and popular during the working week.

A key factor to consider is that the Holborn Viaduct station sat next to the tunnels, not over them. So, in 1984, British Rail proposed reopening the tunnel, and shifting the station sideways so that it would be more like a tube station than a railway terminus.

This wasn’t the original plan, it was only after the Greater London Council stumped up the cash for a feasibility study did they find out that the works could be done for an affordable £4 million, instead of the presumed £30 million. This was thanks to decisions such as avoiding the extension of Southern Rail’s 3rd rail into North London and the construction of an elaborate interchange at West Hampstead.

So, plans approved, and works started in 1986 to relay the missing tracks in the tunnels and add in modern signalling systems.

On 16th May 1988, through services resumed for the first time since 1916, under the new Thameslink brandname.

But almost as soon as services had started, Thameslink closed the central London section, from 29th January to 29th May 1990. This was to allow the completion of the building of a brand new station in the centre of London — City Thameslink.

This also saw the demolition of a bridge that was at once both a famous landmark, but also as famous for spoiling a view of St Paul’s Cathedral.

The new station ran under the streets rather than above them, with a steep slope from Blackfriars down to the new City Thameslink station.

The new station can also be seen as a merger of two older stations, for its southern entrance is roughly where the old Ludgate Hill station used to be, and its northern entrance is next to the site of the old Holborn Viaduct station.

The City Thameslink station was also built for the future – a future that never arrived, as it included some safeguarding features for the planned Jubilee line extension which would have run through the City instead of Southwark.

It could still get a connection to the London Underground though, as there is a suggestion that a passenger link to the moderately close St Pauls’s tube station would be possible.

The past few years have been, to put it mildly, difficult as the Thameslink upgrade project worked to cope with surging passenger demand.

But on this it’s 30th anniversary, maybe time to celebrate the original crossrail through central London by putting it back on the tube map again.