I think Jenna has provided far more info than I know about this.
A couple of extra pointers. Do work out first whose pole it is. Electricity utility company poles can have BT wires attached, but not the other way around (as far as I know) - and BT are no longer allowed to camp ANY new wires onto leccy poles anymore.
Having worked out whose pole it is contact the Wayleaves Department. The pole only supplies you (and no-one else), you definitely won't get anywhere - they will say 'well you want the service don't you?'
If the pole supplies only others (and not you) then a wayleave should have existed, they may be willing to set one up, but as some of the links suggest, they pay only peanuts for this.