E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Thank you much (the French grand merci). Thus Shakespeare, Be it so, Titus, and gramercy too (Titus Andronicus, i. 2). Again, Gramercies, Tranio, well dost thou advise (Taming of the Shrew, i. 1). When Gobbo says to Bassanio, God bless your worship! he replies, Gramercy. Wouldst thou aught with me? (Merchant of Venice, ii. 2.)