"MacGill" envelope to Middlesborough and showing, on reverse, "BRITISH POST OFFICE/CONSTANTINOPLE" and arrival c.d.s. R.P.S. Certificate (1955). Photo" /> cover A fine example tied by barred oval "C" on 1893 (25 Feb.)<I> "MacGill"</I> envelope to Middlesborough and showing, on reverse, "BRITISH POST OFFICE/CONSTANTINOPLE" and arrival c.d.s. R.P.S. Certificate (1955). Photo | Christie's