Elliot 803 happened more than 10 years after EDSAC, so EDSAC was already ancient then; in fact 803 happened at the same time as Orion (the first computer I ever worked on, but not the oldest - 15 months after meeting Orion I was using a Deuce, and the Deuce antedated Orion and 803 by 5 years). The first 1900 was the ICT 1904, an English copy of the Canadian FP6000 which was 3 years later than the 803 (the 1904 was another yet another year later). The first ICL (as opposed to ICT) 1900 was much later - ICL didn't exist until 1968 - so I guess that EDSAC was much more ancient then than it was when the 803 debuted.