Lenszner is a former director of Plymouth Argyle Football Club, and has held other directorships in the recruitment industry. His current role is Managing Director at Ocean City Marine Recruitment.
In mid-2018, Lenszner became a prominent activist for Jewish issues during the Labour Anti Semitism row. He was filmed outside the Labour headquarters on 4 September 2018, calling Chris Williamson a fascist on a megaphone whilst Williamson was being interviewed by the media. When interviewed by the Daily Mail following the incident, Lenszner said: 'I'm here to try to persuade the Labour Party that I once voted for to adopt the IHRA [definition of anti-semitism] in full. The guys that sit alongside Corbyn and on the NEC making up this legislation for the party have taken up Jeremy Corbyn's hatred of Israel to such an extent it is spilling over into anti-Semitism.'
In September 2018, he appeared on a BBC Two documentary called 'We are British Jews', during which he visited the state of Israel for the first time and walked out of a discussion with Issa, a Palestinian activist, however Lenszner claimed to The Times of Israel that Issa had called for the expulsion of all Jews from Hebron and for those who remained to be tried as war criminals, which was left out of the final film.