Thanks for your comments guys,i've done quite a few of these jobs over the last couple of years and trust me,i thought like you Richy that ladders would be a cheaper option,but its NOT safe.
Think of when you do drives paths etc your maintaining an even distance with the nozzle end from the work surface this also has to apply when paint stripping from walls,this you cant do off a ladder,remember,99% of the time you have 2 hands on your lance.
Secondly,
you cant work anything above waist level on vertical surfaces you need to be on top,looking down on your work
theres also the splash back for a start,even with a full visor you cant see what your doing properly.
The weight of your hose,up a ladder after 5 mins that gets bloody heavy.
GWCS
Its a good point about a powerpole,i have an extenable HP lance,i use it mainly for general removal of dirt,but again,you really need to be face on to the surface for paint removal as it takes a bit more time,and them lances get extremly heavy to,not only that its not good for the neck looking up for hours.
Richy,no offence but get out your ladder,extend it as much as you can,get up it with your lance etc,see how you get on

If i get one of these jobs again,i'll take some pics and show you all what i mean