15.10.1859 St Stephens Church Islington.
George Henry Mott full age Batchelor a Warehouseman 4 Portland Place... father William Mott a Warehouseman.
Mary Catherine Josephine Quill De Longford full age Spinster 3 Barnsbury Place... father Morris, Henry, Hugh De Longford. a Clerk
As she is full age she must be at least 21 or over, so that helps to narrow it down a bit .
Where her fathers name appears Morris, Henry, Hugh Quill has been entered but then crossed out, so perhaps Quill was her mothers maiden surname as it is part of Mary Catherine J's name.

The witnesses look like Emmeline Lavinia or Davinia Mott and Sarah Pond Burt or Bull,

not sure of this surname.