This timeline is compiled from a variety of sources, all referenced below, whose details do not always match but the main trajectory of his career is clear.
1852 Born (1,2,8) in Huntingdonshire (1) or Scotland. (4)
1867-70 Apprenticed with Bottle & Olley, Great Yarmouth.(2,8)
[early 1870s?] Assistant to Habershon & Pite for 1 year. (8)
1871 (1) or 1874 (2),(8) Started his own practice in Accrington, Lancashire (1,2) at 9 Dutton Street (6). He lived at 9 Cannon Street in the town. (6)
1875 Was he practising in both Accrington and London at 26 Finsbury Place, London? (5)
1884 Moved to London (1,2,8) initially at 4 Great Winchester Street (8), From 1914 at 5 Clement’s Inn, Strand (8) and then from 1926 at 121 Victoria Street,(2,8).
1892 Became a Fellow of the Royal Institute of British Architects on 18th January. (8)
1901 Reginald Palmer Baines (1879-1962) (4), his son, became a partner and the practice became G & R P Baines. (1,2,8)
1929. retired. (1,2,8)
1934 17 March died. The company continued, latterly as George Baines & Syborn. (2) until at least 1970. (8)
(1) The Chapels Society Newsletter 52, January 2013
(2) Dictionary of Scottish Architects http://www.scottisharchitects.org.uk/architect_full.php?id=203023(3)
(4) Chapels Society Newsletter 57, September 2014.
(5) The Architect, January 30, 1875 retrieved from http://archiseek.com/2009/1875-bath-street-baptist-church-glasgow/:
(6) http://davidrobertmorris.co.uk/2018/04/01/cannon-street-baptist-church-accrington/
(7) Church Building and Heritage Review article at http://www.lightperceptions.co.uk/wp-content/…/CB150_ST-ANDREWS-OXSHOT-A4.pdf
(8) RIBA Biographical note in RIBA Library
George Baines - Non Conformist Architect 
Hello Andrew
Thanks for this comprehensive site which I came across while trying to establish where a picture was taken, almost certainly between 1948 and 1950. It’s a wedding photo featuring my Mum as a bridesmaid. She died 20 years ago and nobody in the family has any idea where the wedding took place or indeed who the bride, groom or anybody else in the picture are. The stamp on the back is of a photographer in Mitcham which led me to look at churches in the area. What little architecture can be seen suggests that this is a George Baines church.
My Mum was born in a small mining village in Scotland and then lived the rest of her life in Edinburgh. We have no idea how she ended up as bridesmaid at this church, probably in London and would really like to find out. The obvious first step is to establish the church.
I would be really grateful if you could take a look at the photo and see if your expertise could narrow it down! If so, how would I send it to you?
Many thanks
Callum Orr