First new Piccadilly line train is covered in graffiti as it arrives in London

The first new Piccadilly line Tube train has been covered in graffiti as it arrived in London .

The train – the first of 94 new trains bought as part of a £2.9bn upgrade of one of the London Underground’s busiest lines – was being transported from the Siemens factory in Vienna when it was targeted.

British Transport Police has launched an investigation and is appealing for witnesses.

The incident is understood to have happened early on Monday morning while the train was near Latchmere rail junction, near Clapham.

Sources said the graffiti spray paint had since been removed and the nine-carriage train has been restored to “mint condition”.

British Transport Police said: “We received reports at around 6.45am yesterday (14 October) of criminal damage to several train carriages.

“Enquiries are ongoing, and anyone with information is asked to contact BTP by texting 61016, quoting reference 75 of 14 October.”

Transport for London chiefs had been looking to celebrate the arrival of the first new train in the capital at the TfL board meeting on Wednesday.

The train will undergo a year of “intensive testing” before being the first of the new fleet to enter passenger service later next year.

The new trains will be the first on a “deep level” line to have air conditioning and walk-through carriages. Trains on the “sub-surface” lines, such as the Circle and District, already have these passenger benefits.

About 20 per cent of the new Piccadilly line trains will be assembled in Vienna, with the remainder assembled in Siemens’ £200m new factory in Goole, east Yorkshire, that was visited by Mayor Sadiq Khan and Transport Secretary Louise Haigh earlier this month .

At the time, Mr Khan said he was “so excited” about the arrival of the new trains. The Piccadilly line is used for more than one in 10 of all Underground journeys.

The Piccadilly line upgrade also involves upgrades to the depots at Cockfosters and Northfields.

The first of two new cab simulators has been commissioned by TfL to enable drivers to be trained how to operate the new trains, which will replace the existing 50-year-old flee.

Station platforms are having to be altered to cope with the different geometry of the new trains. Caledonian Road station, in Islington, will have trains non-stopping northbound then southbound over the next five weeks .

TfL wants to order up to 18 more Piccadilly line trains and to upgrade the signalling system, to enable peak frequencies to increase to 36 trains an hour, but these plans are currently unfunded.

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