Aaargh! Found the problem, it was a scope problem. I was passing the correct variables and echoing them showed the values were fine, but the update statement was outwith the scope. Working like a treat now
It’s good to see that you’ve found your error. Though I would highly advise (and encourage) you to avoid using the original MySQL extension. Have a read of the sticky at the top of this section as to why it would be in your best interest to switch over to a newer API.
Once you’ve migrated over to either the mysqli_* extension or more preferably PDO you should be using prepared statements when dealing with user submitted data that’s being used in a query, once the user submitted data has been validated