Koizumi and Tani were teaching their Jujutsu method at the Budokwai until 1920, when a delegation formed by Jigoro Kano,the founder of Kodokan Judo, Hikoichi Aida and E.J.Harrison, both Kodokan Dan grades and members of the Budokwai,influenced them to covert to Judo. This was achieved and the Jujutsu men were awarded their Judo 2nd Dans, in recognition of their technique and status. From there on Judo was formally taught at the Budokwai and this can be recognised as the starting point of British Judo. Meanwhile Masutaro O'Tani had been looking to continue his Martial Arts training and subsequently joined the budokwai in 1921. Within 5 years he had risen to the position of assistant instruct to Yukio Tani and become close friends with this character. In 1948 the British Judo Association (BJA) was formed, uniting the majority of Judo clubs in Great Britain and installing GunjiKoizumi as President. Two years later Yukio Tani passed away, having previously suffered a debilitating stroke. Over the next few years O'Tani became disenchanted with the Judo that was being promoted by the BJA and it's anglicising of the Japanese sport he loved. He was also said to be unhappy with the level of support and care that had been extended to his old friend Tani. Consequently,in 1954 O'Tani severed his links with the BJA and formed his own organisation - the Masutaro O'Tani Society of Judo (MOSJ).
Around that time the London Judo Society (LJS), a BJA group co-founded by George Chew and Eric Dominy, decided to invite a high ranking Japanese Judo player/teacher to their society, to become their chief instructor.