Tom Watson just told the Commons at PMQS:
“The evidence file – used to convict paedophile Peter Righton – if it still exists, contains clear intelligence of a widespread paedophile ring. One of it’s members boasts of his links to a senior aide of a former Prime minister, who says he could smuggle indecent images of children from abroad. The leads were not followed up, but if the files still exist, I want to ensure that the Metropolitan Police secure the evidence, re-examine it, and investigate clear intelligence suggesting a powerful paedophile network linked to Parliament and Number 10”.
Early indications are that this refers to the Heath/Thatcher governments.
Update: Here’s the video of the question: