A three-man Guernsey team, which also included Casey de la Mare, travelled to the Portuguese capital for the three-day international competition, the first time the Amalgamated Club have travelled there.
Le Poullain and Lesbirel both competed in the 69kg division in the A and B classes respectively, while de la Mare was in the A section of the 75kg category, all with differing fortunes.
In his final, Le Poullain came up against a German national boxer who fought at last year's European Championships and pushed him close, but lost on a split decision.
As for Lesbirel, he was not fazed by the occasion as he beat Quintino da Gloria in the semi-final to reach the 69k B category final.
There, he took on La Sombra Martinez from the Dominican Republic and also lost out by a split points decision.
De la Mare lost to a home Portuguese boxer in the quarter-finals and lost on points.
'I felt that both Billy and Jimmy did enough in their respective fights to get the decisions, but I won't grumble too much because they were both close fights that could easily have gone either way,' said coach Ben Duff.
More in Thursdays Guernsey Press.
