In 2014 Parker was appointed chairman of the National Trust, an unpaid role. In May 2021 the National Trust announced that he would be stepping down in October 2021.[41]
Parker became chairman of Post Office Ltd in October 2015,[42] in the midst of a long dispute between the Post Office and a number of subpostmasters over problems with its Horizon computer system.[43] In June 2016, he told subpostmasters that replacing the Horizon system would "incur considerable risk".[43] The faulty Horizon system was responsible for hundreds of subpostmasters being accused of accounting fraud and theft since its installation in 1999, and dozens of false convictions.[44] In December 2019, the Post Office agreed to a £58 million settlement, and a High Court judge ruled that bugs, errors, and defects in the Horizon system caused shortfalls in branch accounts.[45] In October 2020, after the Post Office conceded appeals by 44 former subpostmasters to overturn convictions linked to the Horizon accounting scandal, Parker issued an apology, stating "I am sincerely sorry on behalf of the Post Office for historical failings which seriously affected some postmasters. Post Office is resetting its relationship with postmasters with reforms that prevent such past events ever happening again. Post Office wishes to ensure that all postmasters entitled to claim civil compensation because of their convictions being overturned are recompensed as quickly as possible. Therefore, we are considering the best process for doing that".[46][47][48] The prosecution by Post Office Ltd of 732 subpostmasters in relation to the faulty Horizon system is described as the biggest miscarriage of justice in British history.[49] He resigned as chairman of Post Office Ltd on 30 September 2022.[50]
In April 2018, Parker was appointed chairman of Her Majesty's Courts and Tribunals Service (HMCTS), effective 27 April 2018.[51] He left HMCTS in December 2022.[52]
Parker became chairman of Post Office Ltd in October 2015,[42] in the midst of a long dispute between the Post Office and a number of subpostmasters over problems with its Horizon computer system.[43] In June 2016, he told subpostmasters that replacing the Horizon system would "incur considerable risk".[43] The faulty Horizon system was responsible for hundreds of subpostmasters being accused of accounting fraud and theft since its installation in 1999, and dozens of false convictions.[44] In December 2019, the Post Office agreed to a £58 million settlement, and a High Court judge ruled that bugs, errors, and defects in the Horizon system caused shortfalls in branch accounts.[45] In October 2020, after the Post Office conceded appeals by 44 former subpostmasters to overturn convictions linked to the Horizon accounting scandal, Parker issued an apology, stating "I am sincerely sorry on behalf of the Post Office for historical failings which seriously affected some postmasters. Post Office is resetting its relationship with postmasters with reforms that prevent such past events ever happening again. Post Office wishes to ensure that all postmasters entitled to claim civil compensation because of their convictions being overturned are recompensed as quickly as possible. Therefore, we are considering the best process for doing that".[46][47][48] The prosecution by Post Office Ltd of 732 subpostmasters in relation to the faulty Horizon system is described as the biggest miscarriage of justice in British history.[49] He resigned as chairman of Post Office Ltd on 30 September 2022.[50]
In April 2018, Parker was appointed chairman of Her Majesty's Courts and Tribunals Service (HMCTS), effective 27 April 2018.[51] He left HMCTS in December 2022.[52]