Gao Yang was positioned side-back towards the spectators, meaning he couldn't see Mario unless he left his current position to go to the back door of the fortress, lift his binoculars, find the location of the Italian delegation, and then pinpoint Mario from the crowd.
Gao Yang couldn't directly search for Mario, so he needed someone to guide him to the target, and the only person who could do that was Tarta, because he could only see Tarta.
Tarta appeared quickly, mingled among a group of British Army, wearing a beret instead of the standard British helm, but what instantly distinguished him was not Tarta himself, but Jansen beside him.
Jansen was clothed in a Scottish tweed kilt, holding a bagpipe, standing alongside Tarta. As they landed with the first wave of infantry, Gao Yang immediately located their position.
Tarta managed to blend into the British Army thanks to Jansen, for Jansen was a bagpiper.
