William G. Ross (1881-1926), who also composed under the pseudonym, Eric Webster, was born in London, and had been organist of Christchurch, Marylebone from 1901, but was invalided to South Africa after the First World War. There he worked for Johannesburg Radio.
He is something of a "Man of Mystery" as he may have been born in Edinburgh, and reasons why he used a pseudonym are not known to me! ;-)
"A Song of Rejoicing" was published posthumously by Novello in 1930 as part of it's "Selected Pieces for the Organ, Vol. One" series.
Sometime ago, I uploaded another "Berceuse" by Ross, although composed under his "other name" - Richard Webster.
That piece was in the key of A major, and was very unusual for a berceuse.
This one is in the key of E major, and also has some unusual "features," although the entire thing is more "lullaby-like" than the earlier upload.
It is quiet throughout, never rising above a mezzo forte, and even that only briefly.
The Solo clarinet is the featured solo voice, and the Swell strings play a prominent part in this performance.
The score is attached below, as well as photos of Christ Church, Marylebone, where Ross was organist.
Now it has a Rieger organ...
I have no photos of Ross himself.