This is probably the tip of the iceberg.

This is the best summary I could come up with:

Mr Roussev, whose most recent address is a seaside guesthouse in Great Yarmouth, also states he once acted as an adviser to the Bulgarian ministry of energy.

The pair, who moved to the UK around a decade ago, ran a community organisation providing services to Bulgarian people, including familiarising them with the “culture and norms of British society”.

At their most recent Harrow home, neighbours said detectives spent a significant amount of time searching it, with a visible police presence for over a week.

Counter-terrorism police have spoken publicly about the increasing amount of time spent on suspected state threats and espionage, especially relating to Russia.

In 2018, Russian operatives attempted to murder former double-agent Sergei Skripal and his daughter Yulia in Salisbury, Wiltshire, using the deadly nerve agent Novichok.

Later that year, local woman Dawn Sturgess - who was unconnected to the Skripals - died after being exposed to the nerve agent, which had been left in Wiltshire in a perfume bottle.

I’m a bot and I’m open source!

“Deadly nerve agent” should read “Not every deadly at all agent”