Can anyone tell me what the aerial is for located at the rear between the external fuel tanks on the chally, I am building a trumpeter kit and there is no reference to it but it appears on the walk around photos I have researched.I wondered if it was for ground support comms. Thanks in advance.

That is not an antenna, it is a rear hull length/distance marker for the commander when looking rearwards over the decks.

You will find them at the front (left and right) on the latest TES versions as well.

Keith.