Greater Anglia

In August 2016, Greater Anglia was awarded the East Anglia franchise with a commitment to replace all of the existing fleet. As part of this, an order was placed with Bombardier for 111 electric multiple units that were members of the recently launched Aventra family.^[18][19] These new trains were designated as the Class 720 and were originally planned to be divided into two sub-classes; 89 five-carriage 720/5 units and 22 ten-carriage 720/1 units.^[20] However, during October 2020, Greater Anglia amended its order to convert all 22 ten-car units into a further 44 five-car units, stating that this delivered increased flexibility within the originally-ordered total of 665 vehicles.^[21]

The Class 720 is a replacement for a diverse range of units, including the Class 317 and Class 321 units, together with the more modern Class 360 and Class 379 fleets that has been long used on outer-suburban services on the West Anglia and Great Eastern Main Lines.^[20] The Class 720s are constructed at Bombardier's Derby Litchurch Lane Works.^[22] The order has been financed by the rolling stock company Angel Trains.^[23][24] The introduction of the fleet has been accompanied by a roughly £300 million investment in new and refurbished infrastructure, affecting depots, sidings, and stations, to best accommodate the new trains.^[13]

c2c

In December 2017, c2c announced it had reached an agreement with rolling stock financiers Porterbrook and manufacturer Bombardier to procure 60 vehicles of the latter's Aventra family—formed into six 10-car trains—with the intention that they would enter service in 2021.^[25] The order was subsequently amended to comprise twelve 5-car trains.^[26] These will be numbered in subclass 720/6, following an earlier expectation that they would be designated Class 711.^[27][28][29]

Greater Anglia

Production of the first unit for Greater Anglia began in February 2018 and was completed in September 2018.^[30][31]

Early on, it had been intended for the type to enter service during 2019, but the fleet's introduction had to postponed into the following year due to software issues with the onboard Train Control Management System (TCMS).^[13][32] Testing of the first unit commenced on 17 March 2020, on the London Liverpool Street to Southend line.^[33]

Both the testing and production programmes were impacted by the COVID-19 pandemic that took hold during 2020. On 8 June 2020, operational use of the Class 720 was formally authorised by the Office of Rail and Road (ORR).^[13]

On 26 November 2020, the first two units started passenger service on the London Liverpool Street to Southend line.^[34]

On 16 December 2020, they started service on the Braintree branch,^[35] and on 23 December 2020, the Class 720s were rolled out on Southminster services.^[36]

In February 2021, it was reported that driver training had begun for their introduction to the Cambridge route.^[37] That same month, Ian McConnell, Greater Anglia's franchise and programmes director, noted that the Class 720 was already running relatively well and free of any meaningful technical issues, with challenges with the onboard software issues being the chief concern with the type's deployment at that point.^[13]

According to railway industry periodical Rail Engineer, Greater Anglia intend to gradually extend the new fleet's usage to eventually cover all of the Great Eastern routes in Essex and through to Ipswich during the first half of 2021, while the Class 720 would be introduced to the west Anglia route between Liverpool Street and Cambridge in the second half of the year.^[13]

On 23 March 2021, the 720s were introduced on the Liverpool Street to Clacton, Colchester Town and Ipswich services.^[38]

On 25 August 2021, Class 720s entered service on the West Anglia mainline and Hertford East branch.^[39] On 13 September 2021, the 720s started services to Harwich Town and Walton-on-the-Naze.^[40]

c2c

In December 2017, c2c announced an order with Porterbrook for six ten-car Class 720/6 Aventra electric multiple units. The new units are scheduled for delivery between mid and late 2021, meaning they will all be in service three years earlier than the initial planned phased introduction period.^[41] The first 720/6 was delivered to c2c on 19 April 2022, and the fleet was due to enter service in 2022.^{[42][non-primary source needed]}

The order was later changed to 12 5-car units. These new units were planned to replace the allocation of six four-car Class 387 units, which c2c was operating on a short-term lease.

On 6 October 2022, the Southend Echo newspaper quoted a c2c spokesperson as saying that "Our 720 class trains are currently undergoing rigorous testing. We will update our customers as soon as we have more information as to when they will be entering passenger service on the c2c route”.^[43] In March 2023, c2c's managing director confirmed in an interview that it was planned that the Class 720s would enter service later that year.^[44]

On 2 June 2023, it was reported that the new trains would come into passenger service in September.^[45] The first c2c 720s duly entered service on 27 September 2023.^[15]