In 1841, Peter Mather (indexed as Mather Peter, no occupation given) was 49, living at Back Cross Street, Little Bolton with Ann (25), John (23) and Elizabeth (6 mo). Peter was NOT from Lancashire, although the others were.
There was a Peter and Sarah Mather from Prescot who had Ann baptised in 1818. He was a hairdresser. However, there was no John, so it is more likely Sarah is the mother John's baby Elizabeth.
NOTE: There is another Peter Mather of Church Street, Radcliffe, of similar age. That Peter was an Organist in 1841.