He spent approximately 17 years working as a missionary in Uganda, serving in areas such as Mulajje. Toward the end of 1926, he moved from Corby, Northamptonshire, to serve as a parish priest in Scunthorpe, England. He is remembered locally for introducing spiritual innovations like the monthly Holy Hour.  Not a well man, he suffered a brief illness early in 1928, and died on 28 February of that year in Scunthorpe, where his funeral marked the first-ever service for a Catholic priest in the town. 

EAHB 1906 - Mill Hill Mission - Mumias - Father L. Kallen is in charge

North - at Mombasa meeting missionaries of 5th MHF party for Uganda 6-1-1903, arr. Kampala from Mombasa via Kisumu 11-1-1903