"...IN 1888, HE RELOCATED TO A LARGE PREMISES, AT 48 WHITTALL STREET AND LINCOLN JEFFRIES BEGAN DESIGNING AND MANUFACTURING AIR RIFLES..."

Then apparently they move to "A MUCH LARGER PREMISES AT 121 STEELHOUSE LANE, FROM WHERE HE PRODUCED HIS WORLD FAMOUS ‘LINCOLN AIR RIFLE’ ".

So - somewhere between 1888, and 'whenever' Lincoln Jeffries designs the Lincoln Jeffries air rifle?