This letter from György Ránki to John Halas from the 27th February 1940 gives an insight into the months before Halas & Batchelor was founded. Ránki was a Hungarian composer who had studied under Zoltán Kodály and was producing music for theatre and film in Budapest in the 1930s - presumably where he made contact with John.
With anti-Jewish laws coming into effect in 1938 and the opportunity for work, Ránki spent some time in London between 1938 and 1939 before moving on to Paris. Whilst in Britain his relationship with Halas was renewed as this letter shows.
Brave Little Tin Soldier, as far as we know, was never made. In fact the only evidence of what the film would have been is the music score mentioned in the letter which is held in the BFI National Archive. Within 3 months Halas-Batchelor, as it was first called was formed at Bush House working on commercials for the J Walter Thompson advertising agency.
The most profitable outcome of the letter was the introduction to Matyas Seiber, another pupil of Kodály of Hungarian birth, who has actually been in the London before John Halas having fled Germany in 1933. The relationship between Seiber and Halas & Batchelor would be a hugely successful one, through the Charley series (1948-9), The Magic Canvas (1948), and most famously Animal Farm (1954).
To learn more about György Ránki then I recommend this interview and profile on Bruce Duffie's website
Matyas Seiber we will come back to in more detail.