Sinha managed a pub in Islington, London with her husband.[7]
Sinha joined the Prison Service in 1999 as a Higher Psychologist at HMP & YOI Holloway, a younger offenders' institute and prison. She later worked as a Senior Psychologist at HMP Wandsworth and subsequently held roles including Head of Safer Prisons and Head of Reducing Re-Offending at HMP Wormwood Scrubs.[1][8]
She later moved into operational management, serving as Deputy Governor at HMP Send, HMP Downview, and HMP Liverpool.[1] In 2013, she was appointed Governor of HMP & YOI Thorn Cross in Cheshire, where she was the first Asian-female prison governor in the UK.[9] Governing HMP Risley in 2016, she dealt with high levels of novel psychoactive substance abuse by prisoners.[9] She tenured at HMP Liverpool in 2017 and oversaw efforts to address institutional challenges including drug use, rodent infestations, and other sanitation concerns.[10]
In 2020, she moved to headquarters within HM Prison and Probation Service (HMPPS), serving as Acting Deputy Director of the Probation Reform Programme and later worked on the Workforce Programme.[8] In November of 2021, she was appointed Director of Women at HMPPS, where she led policy and operational work relating to women in the criminal justice system.[8]
Also, in 2025 Sinha was appointed an advisor to the Women's Justice Board of the UK Government, which focuses on, amongst other things, reducing the number og women in person and women's reoffending.[11]
Prison Reform Trust
In April 2023, Sinha was appointed Chief Executive Officer of the Prison Reform Trust, a UK-based charity focused on prison reform and criminal justice policy.[8] In this role, she highlighted issues including prison overcrowding, staff shortages, sanitation, the impact of long sentences, and the growing influence of organized criminal groups within prisons.[7] She has argued that prisons are often run in "crisis mode", with limited purposeful activity for prisoners, contributing to despair and hopelessness.[12]
Sinha identified priorities for the organization including work on long or indeterminate sentences for public protection (IPP), leadership development programs across the justice system, probation, and policy leaders, and strengthening work on women in the justice system. She has also drawn attention to the effects of the cost of living crisis on prisoners, including rising canteen prices, low wages, and debt related violence. Sinha instated reward and recognition schemes to encourage positive behavior in prison systems.[13]
In a 2025 interview, Sinha called for a reduction in the female prison population. She was appointed an advisor to the UK Government's Women's Justice Board, which works to reduce the number of incarcerated and recidivate women.[11]