Finally got the info for this rifle from John Dickson and Son.....

The workshop ledger entry
No. 6843, Double Centre Fire Express Rifle, Best, .450, 28in Damascus, ? Bar with long strap on comb, Pistol Hand, Grip Cap
Stock - 1 11/16in drop at comb, 2 5/8in drop at heel , 14 1/4in to centre pull.
Standing & Leaf, No. 1 notch sights, 10 Nov 94, Weight 8lb 13 1/2oz. solid taper case, 4 ½ drams powder for 325 grn, 1/8 extra 385 grn solid
bullet
Made for F. D. Pirie

I've found nothing on the web so far about Mr. Pirie.