 Between 1946 and 1949, the average size of the design team working on the Mark 1 and its predecessor, the SSEM, had been about four people. During that time 34 patents were taken out based on the team's work, either by the Ministry of Supply or by its successor, the National Research Development Corporation. In July 1949, IBM invited Williams to the United States on an all-expenses-paid trip to discuss the Mark 1's design. The company subsequently licensed several of the patented ideas developed for the machine, including the Williams tube, in the design of its own 701 and 702 computers. The most significant design legacy of the Manchester Mark 1 was perhaps its incorporation of index registers, the patent for which was taken out in the names of Williams, Kilburn, Tootill, and Newman.
