OS Maps Premium 12 month Subscription Gift Card

For those like myself that cant wait for the £17.99 offer that comes around every so often, you can purchase a 12 month gift card for yourself (or someone else, if you like) at a discounted price.
This is available as an e-gift card or physical gift card. You can redeem it on existing accounts that have previously had a subscription, not sure if you can stack it on an existing subscription though.