Sadly listing an item as a gift won’t make an iota of difference- we just had to pay £65 duty and handling on a box from my in-laws in the US at Christmas. The box contained 2 chocolate Father Christmases, 2 cards and a bath robe that my wife had owned for 3 years. Given what they charge for this I have no qualms with people scamming the system.
Is the frame used? If so then you can raise an appeal as, depending on age and condition, you may not be liable for as much tax as they are charging. Also, the post office are NOT legally allowed to charge you a handling charge- do some googling and point out to the parcel force depot the legality of it (It’s something to do with withholding mail).
http://www.hmrc.gov.uk/complaints-appeals/how-to-appeal/indirect-tax.htm
It gets to the point where I often just have the following conversation with them-
Me- “How much will cost for me to collect this?”
Them- “£65”
Me- “How much will it cost me to send it back to the US?”
Them- “Nothing”
Me- “And how much will it cost you to send it back to the US?”
Them- “Lots”
Me- “Do that then. Bye”