I have just stumbled on your message with the subject heading "lost and found Tonks" from back in 2002 and i am amazed and excited that there are other people out there searching for the same ancestor as i am.
I am a descendent of Ellen Elizabeth Tonks b 1852 in Birmingham,you list all her brothers and sisters with birth years which match my records. Ellen's father was Frederick Tonks b 1828 and his father John Tonks b 1798, i have now found out through your posted messages that prior to him there was another John Tonks.
I would greatly appreciate any information or material that you may have and would also wish to take you up on the offer of a copy of the lease of Custard House farm if that is possible. In return, i live one and a half hours from Birmingham and would be more than happy to carryout any searches for you. Although i note from your message that you are a descendent of Thomas Tonks i am currently awaiting marriage and death certificates of Frederick Tonks b 1828 and his wife Harriett Perry b 1828 and would be happy to forward copies of the same if you so wished.