Insurance on a Bike You Don't Own

[Keep it stiff]

A friend has just gone abroad for a few months, he has left me his Triumph Scrambler to look after and is quite happy for me to use it. His insurance has lapsed, I looked for quotes today and several attempts came up "sorry unable to quote". In the section on ownership I declared myself as not the owner, I subsequently selected myself as owner and up popped the quotes, around £100 fully comp for a year, which is fine.

Why is it that the insurers are blocking me when I declare myself as not the owner? In DVLA terms I am the "Keeper" not the "Owner", this distinction seems to be lost on insurers. Anyone else come up against this and found a way around it? (Ignoring the obvious of course!)