“I want to express my thanks for the commitment, focus, and energy you have brought to ministerial office,” Sir Keir added.
In his letter, Simons said he “never sought to smear” the Guardian and Sunday Times journalists investigated by APCO Worldwide, and paid tribute to their work.
Labour Together paid APCO Worldwide at least £30,000 to “investigate the sourcing, funding and origins” of a Sunday Times story about undeclared donations at the think tank ahead of the 2024 election.
The US public affairs firm’s report included information about journalist Gabriel Pogrund’s Jewish beliefs and claims about his ideological position.
The BBC has not seen APCO Worldwide’s report in full, but sources familiar with its contents have confirmed the details, which were reported by the Sunday Times.
It also claimed, the sources said, that Pogrund’s previous reporting, including on the Royal Family, “could be seen as destabilising to the UK and also in the interests of Russia’s strategic foreign policy objectives”.
A contract addressed to Simons, seen by the BBC, also agreed to investigate journalist Paul Holden and Matt Taibbi, an American reporter.
Holden said on Saturday that “Josh Simons doesn’t deserve to be an MP, let alone a cabinet minister” adding: “I will now work to make sure Parliamentary authorities hold him to account if our weak and supine prime minister will not.”
He claimed Simons’ actions threatened his livelihood and reputation, and caused him “significant distress”.