Strange remark.
You seem to understand that I am not from the US and that I have a different definition of cash. So, why do you wonder if I mean that you are a crook for buying a house?
The OP gives an amount in GBP, so likely it's a British definition of cash. As the Oxford dictionary says: Cash = money in the form of coins or notes
Yes, different country, different definition. In the U.S. the Internal Revenue Service requires you to report any cash transfer of $10,000 or more. The law is designed to prevent money laundering.
Here is the legal definition of cash, under U.S. law.
https://www.irs.gov/newsroom/cash-payment-report-helps-government-combat-money-laundering
"What’s cash
For Form 8300 reporting, cash includes coins and currency of the United States or any foreign country. It’s also a cashier’s check (sometimes called a treasurer’s check or bank check), bank draft, traveler’s check or money order with a face amount of $10,000 or less that a person receives for:
- A designated reporting transaction or
- Any transaction in which the person knows the payer is trying to avoid a report.
Note that under a separate reporting requirement, banks and other financial institutions report cash purchases of cashier’s checks, treasurer’s checks and/or bank checks, bank drafts, traveler’s checks and money orders with a face value of more than $10,000 by filing currency transaction reports.
A designated reporting transaction is the retail sale of tangible personal property that’s generally suited for personal use, expected to last at least one year and has a sales price of more than $10,000. Examples are sales of automobiles, jewelry, mobile homes and furniture.
A designated reporting transaction is also the sale of a collectible, such as a work of art, rug, antique, metal, stamp or coin. It is also the sale of travel and entertainment, if the total price of all items for the same trip or entertainment event is more than $10,000."