Documents also show PM’s choice for US ambassador was offered ‘higher tiers’ briefing before vetting was finalised

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The then cabinet secretary, Simon Case, appeared to advise Keir Starmer to complete security vetting for Peter Mandelson before announcing an appointment, documents reveal.

The documents released last month by the Cabinet Office as part of the disclosures over the US ambassadorial appointment also show Mandelson was offered a “higher tiers” briefing before his vetting was finalised.

The Guardian revealed last week that Mandelson failed his initial vetting by United Kingdom Security Vetting (UKSV) and that decision was then overruled by the Foreign Office. He was appointed as US ambassador but sacked in September after new disclosures about his friendship with the late child sex offender Jeffrey Epstein.