Up until today I had thought it was no longer allowed to sign for Card payments, but I had to at Leeds station as they only have one card machine for all 8 booths.

Surely this isn't secure?

Why isn't it secure?

because I know a LOT of people who don't sign their cards anymore, and also, if it was secure, why was chip and pin brought in?

Unless its changed recently, they still use signatures at the ticket office at the KC Stadium. The post office and bank lets my parents elderly friend who is 97 use a signature instead of chip & pin.

When you are sent a new card you are clearly advised in the letter to sign it immediately. If you choose not to, it's you that is jeopardizing your security, as if you lose it, someone else can sign it and use it.

Signing for transactions is still the norm in some banks never mind other outlets. Chip and Pin is open to fraud as much as signing is, imo, probably more so, and was brought in as an additional way to transact, not to replace signing yet.

Then they are idiots.
You are still advised to sign as soon as you receive your new card.
C&P is the new primary way to authorise card transactions but signing is still the back up system.

my C&P changes for each transaction, accessed via a dongle (a bit like secure VPN), how much more secure can you get?

You're the only person I've heard of whose bank offers that service. Most of us have only one PIN which can be cloned, spied or intercepted. The only fraud I've had on my account was after my card was cloned - not in an ATM machine - in a C&P machine. This would have been impossible under the signature system.

C&P relies on computers which are never 100% secure. The signature system relies on self diligence, and is controlled by the individual.

Who on earth doesn't sign their cards anymore?

Nowhere near as good as Fish and Cushion.

I walked into a car park and all i had to do to pay for my parking charges, was put it in a slot.

If you walked into a car park, why would you feel obliged to pay anything?