I climb telegraph poles.
my ladder has a v shaped (approx. 120deg) moveable grippy piece at the top to sit around the pole, plus a rope to tie the ladder at the top to the pole.
you wont be able to buy one from BT but perhaps you could make up a V bit and mount to the top of your ladder * do it safely of course.
looking at the link above, we get issued with the ladder stopper( good on VERY flat ground) and the microlite standoff (good for walls)
while up the ladder/ pole, you need to strap yourself on too.
we have a fall arrest lanyard, plus a work belt which attaches to hips and goes around pole.
watch a new guy learning how to do it!