I've placed an(other) order from the rather excellent site SplitReason. And, in an attempt to avoid a repeat of August's ridiculous episode (tentatively titled "Royal Mail Handling Fees, or, exorbitance and stupidity in equal measure") I've decided to give our besieged postal service a rest and handle the admin work myself.
This involves one critical thing - getting SplitReason to mark my parcel as "to be customs cleared by importer". I've put the request in and I'll be updating this post as developments occur. I'm determined to import a single purchase and pay any applicable customs charges directly myself (as is perfectly feasible according to UK tax legislation), I don't need Royal Mail's help.
Stay tuned for updates fellow international shoppers!
November 21, 2012: order placed, request to mark parcel as "goods to be customs cleared by importer" has been sent to retailer. Now to wait for acknowledgement.