[3] After attending the 1851 Great Exhibition Kullberg decided to relocate to London and start his own enterprise as an escapement maker.

[4] He regularly submitted his marine chronometers to the annual competition held at the Greenwich Observatory, winning ten times between 1862 and 1890, a record for any one person in the late 19th century.

Following Peter's death in 1935[6] Sanfrid Lindquist was briefly in charge, until 1940 when the firm's premises at 105 Liverpool Road, Islington were destroyed by a bomb during the Blitz of London.

[3] He died on 7 July 1890 at his home, 83 Tufnell Park Road, Islington, and is buried in a family grave on the west side of Highgate Cemetery.

Right up to his death he was still entering his ever-improving marine chronometers into the annual Greenwich competitions and his final entry was said to be the finest instrument ever tried at the Royal Observatory, with a performance which was actually better than the Standard Clock against which it was measured.