[5] Two types of Class 373 were constructed: The North of London sets were intended to provide Regional Eurostar services from continental Europe to and from north of London, using the West Coast Main Line and the East Coast Main Line, but these services never came to fruition because of long proposed journey times and the proliferation of budget airlines offering cheaper fares; there were also issues with the relatively crude design of British Rail overhead electrified lines and problems with finding suitable routes within Greater London.

Upon the privatisation of British Rail, the BR sets were bought by London and Continental Railways, which named its subsidiary Eurostar (UK) Limited,[8] now managed by SNCF (55%), LCR (40%) and SNCB (5%).

This was required for a couple of years, when 3999 was renumbered and replaced another power car whilst it underwent rebuilding at Le Landy.

In 2008, Eurostar announced that it was beginning the process to institute a mid-life update, which would not include the Class 373 sets being used by SNCF in France.

[14] As a part of the update process, the Italian company Pininfarina was contracted to redesign the interiors;[15] the first refurbished Eurostar was not originally due in service until 2012.

Following the COVID-19 pandemic e300 trains now run from London to Paris and Brussels with the e320s, as well as exclusively operating the winter ski service to Bourg-Saint-Maurice.

[21] In May 2000, two Regional Eurostar sets were leased to GNER to operate The White Rose services from London King's Cross to York.

The lease expired in December 2005 and they were handed back to Eurostar; they were later used to operate high speed TGV services with SNCF in northern France.

[26] Due to restrictions in the power supply on the Hertford Loop Line, only one set was permitted to operate on that route at any one time.

SNCF leased three of Eurostar's "Three Capitals" sets for use on French domestic TGV services (mainly between Paris and Lille).

North of London and Regional Eurostar sets are formed of two power cars and 14 coaches: Named units (All since removed)[35] All Class 373 sets were built as tri-voltage, able to operate on 25 kV 50 Hz AC (LGVs, Eurotunnel, High Speed 1, UK overhead electrified lines) and 3 kV DC (Belgian classic lines) using pantographs, and 750 V DC (UK third rail network) using third-rail pickup shoes.

Five of the SNCF-owned sets are quadri-voltage, able to operate from 1,500 V DC (French lignes classiques) in the south of France, used on London–Avignon and ski services.

Auxiliary signalling information, including the location of neutral sections in the overhead supply and pantograph adjustment zones, is displayed in cab and by the lineside.

The operation of circuit breakers over neutral sections is handled automatically on TVM-signalled lines only, and pantograph adjustments must always be manually performed by the driver.

[40] The Class 373 was designed to comply with the Channel Tunnel safety regulations, and consists of two independent half-sets, each with its own power car.

Although the power cars can be uncoupled, specialised depot equipment is needed to split carriages by lifting the entire train at once.

To combat the hypnotic effect of driving through the tunnel at speed for 20 minutes, the power cars have a very small windscreen when compared to other high-speed trains and TGVs.

[50] On 5 June 2000, 373101/102, while working a Paris to London service, derailed on LGV Nord near Arras, France at 180 mph (290 km/h).

During the night of 18–19 December 2009, there was heavy snow causing widespread disruption to roads, railways and airports across northern Europe.

[ex 6] To celebrate ten years of Eurostar service, a barge was floated down the River Thames in London on 16 November 2004,[ex 7] with a power car on board, specially painted by Ben Langlands and Nikki Bell.

[citation needed] The barge went under Tower Bridge,[65] past the Houses of Parliament and moored beside the museum-warship HMS Belfast.