Complex sentence: Farage's result was the best of all constituencies that the party contested in the 2010 general election, with the UKIP candidate standing in Boston and Skegness also achieving a large percentage of vote, the party's second best in terms of percentage.
Split into simpler sentences: Farage's result was the best of all constituencies that the party contested in that election. The constituency of Boston and Skegness also achieved a large percentage of vote, the party's second best in terms of percentage.