There are very solid reasons...
An October 1959 advert from The Hoffman Manufacturing Company. It notes the use of their roller bearing axleboxes on the 1,200hp Type 2 Co-Bo diesel-electric locomotives built for the London Midland Region by Metropolitan-Vickers.
This advert appears in the following categories: Traction: Class 28 ; Supplier: Hoffmann ; Component: Axleboxes