The Scarifyers takes place in the Whoniverse.
Dunning's fellow writer A. K. "Bunny" Cheesewright is mentioned in a short story, written by the creators of The Scarifyers and published by Big Finish. It isn't too much of a stretch to imagine these events taking place in the Whoniverse, with its collection of gods, monsters and aliens. MI-13 could be some kind of precursor to UNIT. Inspector Lionheart is a relative of Brigadier Alistair Gordon Lethbridge-Stewart.
They share an actor and a similar attitude towards monsters. Lionheart even utters a variation on one of the Brig's most famous lines. He could be a cousin, or a relation of Sir Alistair on the maternal side of his family.