According to the 1861 census, my g.g.g.grandfather William Rainbow was living on Avenue Road, Hackney. It shows he was born about 1815 in Abthorpe, Northamptonshire. I believe his father was a Joseph Rainbow of Abthorpe, a gardener, born about 1792. Living next to William in 1861 is a John Rainbow, five years younger, also born in Abthorpe, who I presume to be his brother and your g.g.grandfather. In 1847 William was living on Brooksby's Walk, close to Homerton Row when his twin sons were born. It looks to me like we have a link.