As an ex Jersey ATCO & Watch Manager who took part in many project meetings , planning discussions & technical briefings on this subject, let me explain what I know.
First, OA32 is correct with nearly all of his explanation.
However, The upper part of the 1937 building still lies within the 1:7 slope from the side of the runway. As does the steeple of St.Peter's church.
In the case of the Terminal, it intersects the northern end of the building between the 2 sets of windows above the "viewing balcony" & rises 1:7 in a southerly diagonal direction until it reaches the southern end of the building at the top corner.
This was never a problem until the CAA increased the safety standards (might have been in the '80s), & Jersey Airport was exempted from complying with these "new" standards because the infringement was from an existing building & plans existed for it to be demolished.
When the new A taxiway was constructed it was deliberately decided to construct it with the bend in it (to avoid the '37 building). This was done despite myself & others suggesting that it should not be, because the Airport management should have taken the opportunity to comply with the CAA new standards (which they would eventually have to do, in any case).
The reason that this bend in the taxiway was constructed (despite it infringing the safety area alongside the runway) was the need to accommodate a straightened taxiway by demolishing a substantial part of the new arrivals hall (which had only been built a couple of years earlier !) to allow the re-positioning of the taxiway through the apron.
However, it was always the Harbour & Airport Authority & the Airport Managements' intention to straighten this taxiway & build another "new" arrivals hall in due course; & thereby comply fully with the CAA standards, eventually.
This looks like what is now beginning to take place. At last !
As regards moving the runway to the North. Don't even think about it (as OA32 states)t. This is just another example of a politician talking about matters of which he has absolutely NO understanding.
I worked in this asbestos ridden building for 30 years & , in that time it was never once hit by an aircraft going around in bad weather !
Nevertheless, it is now time to pull it down.