Theoretically any postal imports from non-EU countries attract Customs Duty, VAT and an £8 customs examination fee.
However Customs Duty isn't payable where the value of the goods is less than £135. VAT isn't payable where the value of the goods plus postage (plus Custom Duty, where relevant) doesn't exceed £15, so you're just in the clear there. The customs examination fee isn't payable when there's no Customs Duty or VAT to pay. So you should have nothing to pay.
However another few pence on the price of the item could have cost you dearly. For example, if the item + carriage came to £16 (and you weren't buying a VAT-exempt item, such as a book), you'd have to pay £3.20 VAT plus an £8 customs examination fee, totalling £11.20.
Take great care when buying from outside the EU!