[citation needed] Leaving his brother in Scotland to run the business, Dewar set out to publicise their brand to the world.

During this period, Dewar was noted for his hostility to "pauper immigration" and played an active part in campaigning for the legislation that became the Aliens Act 1905.

[6] However, as he never married the baronetcy and barony became extinct on his death, at Homestall, in April 1930, aged sixty-six, following which he was cremated at Golders Green Crematorium.

For cycling he donated the Dewar Challenge Shield in 1901, a heavily embossed silver plaque depicting goddesses and allusions to Scotland to include thistles and a profile of a racing cyclist centrally mounted.

It is inscribed "Theatrical Sports Five Miles Cycling Championship Shield" — "Presented by Sir Thomas Dewar MP — To be won Three Years in Succession".

Dewar's marksmanship trophy is a large silver cup standing over two feet tall with two oversized handles and ornately decorated to the Society of Miniature Rifle Clubs (SMRC) of Great Britain.