London, May 20, 1911. One sheet folded to make four pages, 8 x 5 in. (203 x 127 mm). Autograph letter on Crown Chambers stationery, signed by Shackleton ("E.H. Shackleton") to Dorothy Delmar Morgan (née Locker-Lampson), declining an invitation, "Many thanks for yours: Alas I am engaged right ahead/for a long time otherwise I would have been/delighted to accept. Teetotal meals do not frighten me considering that I was for a/period of 32 years a teetotaler myself..." Light dampwrinkling; residue along rear edge from old mount.