I'm assuming the ST refers (as has been the case in many earlier questions from Asker) to classic motor vehicles from the Jaguar stable (one of which is sitting in my garage...).

In Jaguar-speak, the "parcel box" refers to the compartment ("boîtier") in the "console centrale" between the front seats (i.e., not the "glove compartment/box" - "boîte a gants") where we put personal effects whilst whisking through the English (or other) countryside.