Antique brass door knocker, using the device of a dolphin as the knocker.
George Kenrick was a foundry owner, originally in iron in the so-called 'black country' of Birmingham, England. Established in the late eighteenth century the firm continues to this day. Products are notoriously difficult to date, as successful models have never gone out of production.
This a Regency design, c1810, marked on verso '296 Kenrick & Co'. 
 
Height. 235 mm
 
Gilded brass.
 
Excellent condition.