[13] Each car has a length of 24 m (79 ft), the bodyshell of which is composed of aluminium, the assembly of which using both welding and bolting techniques.

These seats are intentionally cantilevered above the floor to provide greater under-seat space for storing personal luggage as well as to ease cleaning.

[14] Every seat is provided with its own seat-back table and power sockets, while on-train Wi-Fi enables online connectivity throughout the journey.

[13] In September 2017, Greater Anglia unveiled an early mockup of the interior intended to be fitted to the Class 720 fleet.

[14] The units also featured underfloor heating, eliminating the need for the bodyside heaters and thus increasing floorspace for more passengers.

As part of this, an order was placed with Bombardier for 111 electric multiple units that were members of the recently launched Aventra family.

[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] 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.

[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] 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.

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.

On 6 October 2022, the Southend Echo newspaper quoted a c2c spokesperson as saying that "Our 720 class trains are currently undergoing rigorous testing.

However, owing to the services that they operate, the Class 720s have a higher top speed of 100 mph (161 km/h), and have significantly more seats per carriage (and less standing space).