Thanks for the info. all,
I rang revenue and with my PPS number they were willing to tell me it hadn't been paid, but not the detail of what was owed etc. Apparently he did lodge a deposit immediately but never settled the full amount. So from what I can tell we're not liable for penalties but still need to get it sorted. Mf1, I take it from your post that if the stamp duty is not settled then the deeds won't have been returned to the lender. So if his office burnt down or he mislaid them, we could have a tricky situation. Its 1.5 years since we gave the money to the solicitor so I'm now off to hound him.
Savvy, to answer your question, the reason its not entirely clear how much we owe is that it was a new home without a floor area compliance cert, we were 2nd time buyers so hence the following applied:
"The stamp duty is charged on the site value or one quarter of the total value of the property (less VAT) whichever is the greater."