Alexis Jacob was a son of Sydney Long Jacob
There is more detail and an excellent account of some of his work in Peter Conlan's ' "What are you doing for Christ in Birmingham?" The History, Strategy, and Legacy of a Missional Brethren Assembly Founded by Alexis Jacob in 1924'. This is chapter 13 in Neil Dickson, T.J. Marinello, [eds], The Brethren and the Church, (Glasgow: BAHN, 2020) 217-227. Timothy Stunt.
There is a circular in memory of Alexis Jacob at the above-linked site, here: