One thing to keep in mind about Volhynia Gubernia - in the early 1920's western parts of it were already in Poland (until 1939), while eastern were part of Ukraine.  Take a look at this map that shows the borders after the 1921 Riga Treaty: https://en.wikipedia.org/wiki/Peace_of_Riga#/media/File:Rzeczpospolita_1922.png.  These people might have traveled to England from the Soviet Union or Poland at this time.

Mike Vayser