Hi guys, I recently let my subscription lapse to see what deals they were currently throwing at Silver members and this came up - 3 months Gold membership for £6.00. You can find it on the dashboard (I believe it's on the front page).
This was valid as of last night and a couple of my mates have the exact same offer so I'm assuming it's applicable to all Silver members. If not let me know, but seems like a very good deal to me!
Oh and don't forget this will automatically renew at the full price once the three months is up, but is now easily cancelled (unlike before) from your console or xbox.com.