In 1892 Thomas Borthwick moved his company to London. In 1895 his sons became partners in the company, which took the name Thomas Borthwick & Sons Ltd. in 1904. The company went on to establish freezing works in New Zealand and Australia. Branch offices were established in Christchurch, Sydney, Melbourne, and Brisbane. Borthwicks also had several ranches in New Zealand and Australia and practically controlled the trade from the livestock market in Australia to Britain.
Today Thomas Borthwick & Sons Ltd. continues in Australia as a leading meat processing company which exports its products worldwide.
Despite the long history of the company, I am unaware of any overprints on stamps other than the ones shown and SG 506a.
by Mark Matlach