To add to other good answers here, I think there is something of the practical versus academic bias to be seen here as well. It was always hinted, but recently verified as documents have been declassified, that much of Mr. Turing's efforts after World War II were attempts to explore the consequences and abilities of devices he managed to actually build during the war, but was unable to continue working directly on after the war, so he did what he could skirting what tools he could use and how he could tell people based on what had been classified.

I think that makes Mr. Church and his American team's work all the more interesting because they hadn't built practical machines and presumably never saw practical machines and worked almost exclusively in theory.

But it's tougher for our culture sometimes to credit the theorists and academics than it is to credit practical genius. Especially with the declassified documents of the incredible practical computing work Mr. Turing accomplished during the war (and helping the war effort), it is easy to give him a lion's share of the credit and ignore some of the equally fascinating/important academic work of Mr. Turing's contemporaries. (Especially knowing in retrospect that the practical work fed the academic work and vice versa.)