Being sensible again, something like this
Pacsafe Cable seems a handy thing, although it's just a metal cable and I doubt it's 'sheathed' to protect any leather etc.
The Thule ones look good. Never seen one in the flesh, so I'd guess a walk around Halfords would pay dividends on that.
It's not the ultimate security I'd be after, but the grabbing of a bag at traffic lights or when you've left it over lunch etc.
The golden rule is to keep anything vaguely valuable to others under cover, on the basis that if no-one knows it's there, why try & steal? The cabled bags are a second line of defence and make sense...unless you have a large anti-social dog also attached...
