Buckingham MP John Bercow completed a 5km swim on Saturday, in support of Padbury-based charity Brain Tumour Research.
Mr Bercow, who is a patron of the charity, swam 200 lengths as part of a Marathon Sport Challenge at the Swan Pool and Leisure Centre.
Another patron, Olympic swimmer Craig Gibbons, was on hand to award him with a medal.
Mr Bercow said: “I’m delighted and relieved to have completed the 5,000 metres. As people who were patient enough to count can testify, I am a very plodding swimmer, but I was determined to complete the course because Brain Tumour Research is a fantastic cause which needs all the support it can get.”
Mr Bercow has already raised £4,930. To sponsor him, visit www.justgiving.com/john-bercow1
Two local girls each swam 170 lengths and had their picture taken with Craig Gibbons. April Barnes, aged nine, attends Buckingham Primary School, and Sophie Holmes, aged 10, attends Bourton Meadow School.