Whilst looking for The Murder Room mysteries I came across this freebie:
The Spymaster Murders
Don't know anything about the author or the book. Here's the blurb:
An impossible murder, a killing in a locked room and the disappearance of a senior military figure become a baptism of fire for Wing Commander Derek Rigby. The story unfolds at Aldergrove in Northern Ireland, as a distant war rages over the Falkland Islands in the South Atlantic. Rigby must solve the murders, expose a deep-cover Soviet agent and sort out his catastrophic personal life in a case which sets him on the path to becoming the senior counter-intelligence operative we meet, decades later, in the Monica Jones Mysteries (The Sheffield Conspiracy and The Priests of Orion). All the clues and signposts are laid out for the reader in a puzzle which pays tribute to the Golden Age of British detective fiction.