Hi Bob,
According to the IGI Charles Mather Machell was baptized Saint Mary Magdalene, Bermondsey, London, England.
According to Ancestry he was baptized St Mary Magdalene, Southwark, Surrey.
I haven't found either of Charles Mather Machell's parents in the censuses.
I have found a death for a Martha Maria Machell in 1857 in London. On the burial record (Nunhead Cemetery, Linden Grove, Southwark, Surrey) her age is given as 67, born 1790. But I have also found a baptism record for Martha Maria Laughton 30 Dec 1781 St Bride Fleet Street, London.
Bridget