Hi Doreen
My great great grandfather was William Stewart Tull (1824 - 1896). He married Charlotte Key (1834 - 1891; daughter of Edward Key and Rebecca Ratnett). The Tulls, Keys and Ratnetts were quite close and can be found at one another's homes in Northampton, London and Huntingdonshire in various censuses.
William and Charloitte had 8 children and for some reason (maybe related to mixed fortunes which William Stewart Tull was subject to), Charlotte's sisters Rachel and Emma Key brought up my great grandfather Harry Tull.
Harry went on to have two children - my grandfather Leslie Stuart Tull and my great aunt Sybil May Tull. Unfortunately Leslie died before I was born, but I knew my great aunt Sybil quite well, and she remembered the Key sisters well.
I have quite a lot of additional information about them (including numerous photos) if you are interested.
Regards,
Liz