Stone: Church of Christ Scientist - SW1
Erection date: 13/6/1909
This corner stone of granite from Concord, New Hampshire, U.S.A. was laid on November 29th 1904 and the church was dedicated on June 13th 1909.
The two dates indicate the beginning and end of construction, often marked with two different stones, but here they've just added some text - very economical.
Site: Church of Christ Scientist - SW1 (1 memorial)
SW1, Sloane Terrace, 5, Cadogan Hall
The corner stone is below the two arches on the left of the photograph.