This visit was undertaken between the two parts of the Niels Bohr centennial celebrations in Copenhagen (see MS. 11619/54/J.62-63). Correspondence includes discussion of 'The improbable war' and nuclear weapons.

The centenary of Niels Bohr's birth was marked by events in many locations. Peierls attended those in Copenhagen and several in the UK (see MS. 11619/54/J.64-66).