According to Official Guinness Records,
The fastest marathon dressed as a bottle (female) is 3 hr 57 min 57 sec achieved by Natasha Pitman (UK) at the Virgin London Marathon, London, UK, on 25 April 2015. Natasha ran on behalf of the Help for Heroes charity.
For a complete list of 2015 records, please visit 2015 Guinness Records in United Kingdom.