Interesting about Vivienne Trulock not finding any link.

For interest, this is what IGC has on the firms:
Name William Trulock
Other Names Trulock & Son; Trulock & Harriss; Trulock Brothers; Trulock, Harriss & Richardson; Trulock, Harriss & Richardson Ltd;H Trulock, Harriss
Address1 Britain Street
Address2 11 Essex Bridge
Address3 9 Dawson Street
Address4 13 Parliament Square
City/Town Dublin
Country Ireland
Trade Gunmakers
Other Address 22 Bury Street, St James's, London; 4 Pickering Place, St James's Street, London
Dates 1814-1918

Notes

William Trulock reportedly established his firm in 1814 in Britain Street, Dublin, Ireland. He may have previously lived and worked in London, but this has not been confirmed. An address at 11 Essex Bridge has been recorded but dates are unknown. At some time, probably around 1820, the firm became Trulock & Son, and they moved to 9 Dawson Street. In about 1840 William Trulock's son-in-law became a partner in the firm, and it was re-named Trulock & Harriss. It is almost certain that William Trulock had died and that his son of the same name and ? Harris inherited the business.

In about 1855 Samuel, Richard and William Trulock (sons of William (II)?) took over the firm and renamed it Trulock Brothers. In 1863 the brothers together with John Gibson patented a drop-down barrel action. In 1867 the brothers patented their "Lockfast" action (No. 1904) (see Dougall who also patented a "Lockfast" action). From about 1875 to 1885 John Forrestall Smythe was Manager of the firm, he left to buy the business of Francis Brebner in Darlington.

In 1892 the firm took over the Dublin business of J Rigby & Son, soon after this date they moved to 13 Parliament Square, Dublin. By 1900 it appears some of the Trulock brothers had left or died, and Harriss' son and ? Richardson had become partners, the name of the firm becoming Trulock, Harriss & Richardson.

In 1909 a shop was opened in London at 22 Bury Street, St James's. In 1911 the firm became a limited liability company, moving to 4 Pickering Place, St James's Street. In 1916 the company was put into liquidation and the business was taken over by a new firm named H Trulock Harriss. It was not recorded as trading after 1918.

Other Info

The firm sold cartridges under their own name and under the names "Special Brown" (post 1910), "Special Blue" (post 1900), "Empire" (post 1919) and "Tru-iss" around the time they were located at Pickering Place.

Tim