According to Official Guinness Records,
The largest jacket measures 12.95 m (42 ft 6 in) from collar to bottom, 15.32 m (50 ft 3 in) across from sleeve to sleeve and was created by St. George's C of E Church (UK) in Stockport, UK, on 29 June 2011.
For a complete list of 2011 records, please visit 2011 Guinness Records in United Kingdom.