On 26 November 2020, the first two units started passenger service on the London Liverpool Street to Southend Line, on 16 December 2020, they started service on the Braintree branch, and on 23 December 2020, the Class 720s were rolled out on Southminster services. In February 2021, it was reported that driver training had begun for their introduction to the Cambridge route. 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. 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. On 23 March 2021, the 720's was introduced on the Liverpool street to Clacton, Colchester town and Ipswich services.
A unit was on the Cambridge line on Wednesday and another (556) on Hertford East. I saw the latter quite early on at Broxbourne, it having arrived after working 2O88 Stratford - Broxbourne.Have there been any 720s in service on the WA side yet?