Lacy was born in Edgbaston, Birmingham and educated at St George's College, Weybridge. He practsied as a stockbroker in Birmingham, becoming a partner in Cutler & Lacy and chairman of the Birmingham Stock Exchange. He founded and chaired the British Trusts Association in 1917 and the British Shareholders Trust in 1921.
He was created a Baronet in the 1921 Birthday Honours for his contributions to finance.