Hi Trish,
Many thanks for this.
Yes, I did wonder whether his brother would help to identify the right Joseph, but so far I haven't found their baptisms either.
I did find the marriage of Joseph and Lucy, thank you, and I noted the baptism of Lucy. Given how close Wootton St Lawrence seems to be on the map, it does seem credible that she would say she was born in Basingstoke, doesn't it? Joseph and Lucy did call their third daughter Ann, so that might also be a pointer. (And I can't imagine it's a very common name!)
Thanks again for your help,
John