(I could not find specs.
right away on the HP10008A).
I think I might have had A's on the brain - they are infact HP10008B's which according to the result of a search on the Agilent site are a 1:1 voltage passive probe with 1.8M leads.
Thanks all for the incredibly informative responses to my query...The response was much more than I hoped for and I feel like I'm going into this purchase far better prepared that I would have otherwise.
cheers
Paul