Sansum was not selected for the recent Grand Prix in Manchester in the highly-competitive -80kg category, team officials preferring the claims of Andrew Deer and Olympic bronze medallist Lutalo Muhammad.
But the former kick boxer, who has missed most of this year with a shoulder injury, beat European champion Cook to underline his credentials in an interesting selection battle.
Elsewhere, British team-mate Mahama Cho secured heavyweight silver, adding to his Grand Prix gold in Manchester, and Charlie Maddock won -57kg bronze.
And Bianca Walkden rebounded from a disappointing performance in Manchester claiming the +67kg title with a win over Olympic silver medallist Anne Caroline Graffe.
© Sportsbeat 2013