Hi Andrea I'm also researching Birketts but in the Lake District. Going alittle bit further back to 1793. William Birkett married Agnes Gill 22nd May 1820 (second marriage as he was a widow) Children bapt at Colton Agnes Birkett 10th June 1821 Edward Birkett 20th April 1823 Margaret BIRKHEAD 7th Dec 1828 Hannah Birkhead 7th Aug 1831 William Birkhead 19th Jan 1834 Anne Birkhead 23rd July 1837 (died in chilbirth along with Agnes Gill) William a widow again.
His son William Birkhead b 1834 married Isabella Garnett(born Kendal) But they married in BLACKBURN 1st Sept 1860. Not sure when William and Isabella came down to Blackburn we find him on the 1841 census at Low Wood aged 7, then by 1860 living in Anvil Street Blackburn aged 27.
Also notice the name change.
I will keep your notes for future reference. Kind Regards Toni Blackburn