Cash offered for house purchase

[Soontobe60]

I wonder if anyone knows the answer to this. I am selling my late mum’s house, and the buyer has been a bit of a nightmare. He speaks no English, is a first time buyer and is very difficult for the estate agent, his and my solicitor to get hold of. Last week he was given a deadline of today to pay his deposit with his solicitor and to exchange by Friday, completing the following week. Both my and his solicitor say they are able to meet these deadlines comfortably.
He asked for my phone number today so I agreed with my EA that she could pass it to him.
He has phoned me up tonight and basically wants the sale to go through but at £15k less on paper, and he hand me £15k in cash. I said this wasnt possible, that all the deposit needs to be handed to the solicitor.
Am I correct? Is there a reason why his suggestion may not be legal, or even a good idea?

Im assuming he means to hand over the money to me in actual notes - not via a bank transfer!

No. Money laundering. Your solicitor would say no and so should you. Very dodgy. Find another buyer

Hell no.

And put the property back on the market ASAP. Tell the solicitor and estate agent what he has tried to do.

That’s wild, no solicitor would allow that. You should tell them asap.

Stamp Duty avoidance? Or money laundering?

You're right to reject this suggestion!
Being generous, he's trying to avoid stamp duty (which is fraud) but there could be others illegal reasons for his request such as money laundering.
Let your solicitor know what's gone on. And your probably need to accept that he is not a genuine buyer.
If it was me, I'd be withdrawing from this transaction.

I have explained that this isnt an option. I’m annoyed though as the EA saw proof of his deposit and mortgage before we accepted his offer! I believe he’s a shop owner - so perhaps hes avoiding declaring this money.

Anyone want to buy a nice bungalow?😂

Update
I emailed my EA and solicitor about the buyer, and consequently his solicitor has refused to act for him anymore. So I’ve got a partial solicitor bill to pay and the house is back on the market with 7 viewings booked in for next week.