Grok gives the background as follows :

Background and Role: Tom Dewey was elected as a Labour councillor for the De Beauvoir ward in Hackney in May 2022. He had previously worked as an adviser for Hackney Council, working with the cabinet and mayor, and also served as the election agent for Hackney South and Shoreditch MP Meg Hillier. He was known for his involvement in housing and planning.

Arrest and Resignation: Dewey was arrested by the National Crime Agency on April 29, 2022, just before his election, on charges related to possessing indecent images of children. He resigned from his councillor position on May 16, 2022, after his arrest was made public, triggering a by-election.

Legal Proceedings: He pleaded guilty to five charges of making and possessing indecent images of children, including some in the most serious category. His sentencing resulted in a 12-month suspended sentence, a Sexual Harm Prevention Order, and orders to carry out unpaid work and rehabilitation activities.

Public and Political Reaction: His arrest and subsequent resignation led to significant scrutiny and criticism of Hackney Labour, with calls for inquiries into how much was known about his arrest before the election. There were also questions about the delay in informing the Labour Party of his arrest.

Associated Controversies: Dewey's case was part of broader discussions about safeguarding and the Labour Party's handling of such matters, with some accusing the party of trying to cover up or delay the information about his arrest.