Tetley tea,tea leaf, thief as in to rifle through something, from the old French. Nothing to do with lager, Guinness perhaps .
When a call was issued for the formation of local Volunteer Rifle Corps in 1859,[1] the City of Leeds in the West Riding of Yorkshireresponded enthusiastically. A unit calling itself the Leeds Rifles was quickly raised with support from the city's business leaders. It was claimed that the whole of 'A' Company was recruited from employees of Joshua Tetley & Son's brewery, beginning a long association between the Tetley family and the regiment. Wikipedia