Stamp duty refund

[Rollin]

I bought a mixed use freehold property in 2013 (office on ground, flat above). The final solicitors bill included a payment for stamp duty at 1%. At the time I was aware of certain exemptions and questioned the solicitor about the charge. They assured me that stamp duty was due and assuming they knew what they were doing, I paid up.

Something reminded me of this yesterday and I went to use the HMRC calculator which shows that no stamp duty was due for the transaction, due to the value being less than 150000.

So the question is, who do you think pocketed my money?

If the payment had been made to the HMRC, would they just accept it without checking if the transaction required stamp duty?