Christian McArdle wrote:

If you sold a house to someone for £1 and they gave you a gift of £200,000
the next month, you'd probably end up in prison,

For what crime?

so it isn't possible to
just give stuff away, especially if there is some implied contract.

Contract law is different to criminal law.

On the inheritance tax side, if the daughter pays £35,000 for a house worth
£200,000 and her parent/s dies within 7 years, she may have to pay some
inheritance tax on the difference.

The threshold for inheritance tax is 254,000 this year, isn't it?

I have no idea if stamp duty is
on the sale price or the value of the property, if this is much lower than
the sale price. I'm sure an accountant or solicitor can advise.

What is this? National Hard-of-Thinking Day? Firstly, your scenario
above doesn't match the OP. Secondly, stamp duty is payable on the sale
price, obviously. Think of when you last bought a house - I bet you
didn't pay the asking price. You make an offer, it's accepted; that's
the price.

--
Ben Blaney
GSF1200 VFR800 CBR600 CD200
"We stopped only for fuel"