According to Official Guinness Records,
The fastest half marathon in a suit is 1 hr 18 min 10 sec and was achieved by Michael Tozer (Australia) at the Westlink M7 Blacktown Running Festival, in Blacktown, New South Wales, Australia, on 31 July 2016.Michael ran the half marathon to raise awareness for Syndrome X.
For a complete list of 2016 records, please visit 2016 Guinness Records in Australia.