So basically, "The Tower" was a primitive version of the early fish-era track "Grendle", and the only known Irving-era demo track to never have been bootlegged, let alone officially released. Just like any Irving-era track, it is unknown where and when it was played live, if it even was. Maybe we could find out by time a recording of either of the three concerts listed below.
Regardless if you remember going to an Irving-era concert, or even if this is the first time you ever heard of Marillion, enjoy having a healthy discussion.