Hi Flackdodger
Have done some more research.
Samuel Sykes married Sophia Browne 30 Jul 1822 St Peters' Church, Leeds
Samuel Sykes and Sophia had the following children christened in London, St Mary-le-Bow
1. James Sykes 27 Jul 1823
2. Caroline Ann Sykes 29 Apr 1825
3. Henry John Sykes 15 Mar 1827 (he of the gravestone) Father a merchant
Samuel Sykes and Sophia had the following children christened at St Peter's in Leeds
4. Harriet Sykes 08 Oct 1828
5. Sophia Sykes 06 Dec 1830
Samuel Sykes and Sophia Browne had the following child at Mill Hill Chapel, Leeds
6. Frederick Sykes 24 Sep 1834
Also in a Leeds 1837 Directory is a Samuel Sykes, Merchant.
Is it possible that Samuel and Sophia married in Leeds, went to London, came back and when Henry John Sykes died moved from St Peter's to the Chapel?
Could it be that the Church we are looking for is St Peter's. I had a quick look on Google Street view and it does have similar windows to the picture but could not see all of it because of trees?
So back to Leeds it is.
As to the photograph:- There are over 90 people on it which makes me think it is quite a large organization. Mill perhaps.
Will have a detailed look at every person for clues.
Duncan 39