In Season two, Episode one of Downton Abbey, after having spent two years on the battlefront, Thomas deliberately gets shot in the hand by holding up a lighter and inviting the enemy's bullet. However, different synopses frame the motivation of this event differently:
Matthew and Thomas share tea in the midst of the fighting, and when Thomas expresses the irony that the footman is sharing tea with the lord he once served, Matthew tells him that "War has a way of distinguishing between the things that matter and the things that don't." Thomas, who was already clearly sick of the war, takes these words to heart and purposely gets himself wounded so that he no longer has to fight.
Another comes from PBS.org's page for Masterpiece Theatre:
But after two years in the trenches, [...], he must use his scheming ability to devise a plan to escape the Battle of the Somme. Should he survive, he won't return unchanged.
My questions are thus:
Was Thomas' plan to get injured/leave the battlefront suggested in any way prior to his meeting with Matthew?
How does Thomas' conversation with Matthew compel him to act, whether a pre-mediated plan or an impulsive one?
In other words, are we to believe that he may not have done this (that moment or at all) if not for the happenstance of reminiscing with Matthew?