The judge, Mr Justice Garnham, described Lavrynovych as a “useful idiot” who could be easily manipulated.
He said he had been “easily bought” and “accepted the job as you had accepted other grubby little tasks”.
Carpiuc played a “supporting role” in the “utterly reckless” attacks, the judge said.
The court heard a Toyota car previously owned by the prime minister was found on fire on a street he used to live on in Kentish Town, on 8 May 2025.
On 11 May, a fire was discovered at flats linked to Sir Keir in nearby Islington. He had lived there years before.
A day later, a fire was discovered at the entrance to Sir Keir’s Kentish Town home, which he still owned and was being rented out to his sister-in-law, Judith Alexander.
She told the trial of the billowing black smoke going up the stairs while she, her daughter and partner were in the house.
Lavrynovych and Carpiuc were found guilty at the court on Monday of conspiring together and “with others” to damage property by fire between 1 April and 13 May 2025.
Lavrynovych was also convicted of alternate counts of damaging property by fire, being reckless as to whether life was endangered. He was acquitted of damaging property by fire with intent to endanger life.
A third man, Petro Pochynok, 35, was found not guilty of the conspiracy charge.
