Here's a 1974 shot of an old building in Wych House Lane. I don't think this is a candidate for the title of 'Middlewich's first Catholic Church' either. I don't know if this was part of any salt works. It has, to me, more of an agricultural air about it.
The building was still there, in much rebuilt form, until quite recently but a visit to Wych House Lane in July 2011 revealed that it has now disappeared completely