His anonymous handler, known by the initials EL, gave a clue in a message: "Look, you attacked the home of a very high-ranking person in Britain. I'll send you money, you need to leave the city". It was too late: Lavrynovych was arrested within hours. The 22-year-old Ukrainian builder had been weaponised to target the UK's head of government. But by who?

Our investigation has found the arson attack was just one part of an extensive campaign of sabotage, provocation and lies leading all the way to the Russian state. The handler EL, who directed Lavrynovych, offered Russian citizenship in return for other attacks and glorified President Vladimir Putin, messages the BBC has uncovered show. We have identified evidence suggesting that EL is a young Russian diplomat, schooled in information warfare by spies and propagandists, who is close to the highest levels of power in Moscow. His name is Evgeny Lyukshin. He is 23 and the son of a senior official. Russian operatives ran their sabotage and provocation campaign remotely through social media and the messaging app Telegram, we found, creating fake online far-right and Muslim groups, which were used to organise acts of vandalism in the UK and stir up division and fear.

Accounts based in Russia posted lies about the motive for the arson attacks targeting Starmer, which were spread by figures such as far-right anti-Islam activist Tommy Robinson. The Russian embassy said: "We reject any attempt to associate Russia or its foreign ministry with unlawful activities". It said that Russia poses "no threat to the United Kingdom or its people and harbours no aggressive intentions towards Britain". Lyukshin did not respond to our questions, but hours after contacting him, a propaganda channel we had challenged him on disappeared. (BBC)