If you are on this page looking for information about the amount of cash the law allow physical person to import into United Kingdom, you actually want to know the amount of cash someone can import into UK without having to declare it in writing at the point of entry the country.
As a matter of fact if you are entering United Kingdom from EU member counties you can bring in any amount of money without having to declare it at the border.
But if you are coming to UK from non EU members countries, may be from Asia, Africa, America, Middle East and some other part of the world you must declare cash of €10,000 or more or its equivalent in another foreign Currencies
The cash you may have to declare include notes and coins, banker draft and cheque of any kinds.
A family traveling to United Kingdom will have to declare a cash of over €10,000