I’ve just received my parcel from THBC.
The demand from DPD for import duty is genuine so far as I’m able to determine. I checked the source addresses and these were TLS secured and certificated addresses. I went direct to DPD rather than follow the link supplied. There I was told I had to pay £40.77 or my parcel would be returned. I paid, I received an email acknowledgment from DPD and then notification that delivery was being arranged.
Having received my parcel, out of curiosity I just went back to DPDs tracking system - my parcel is seemingly still going through customs!