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pave over their front gardens
Well, if they want to go for the permitted development option, at least they need to make it permeable. Here's national guidance:
https://www.planningportal.co.uk/info/200130/common_projects/45/paving_your_front_garden
https://www.gov.uk/government/publications/permeable-surfacing-of-front-gardens-guidance
They may also have to apply for planning permission if they want to drop the kerb outside a house or make other changes relating to their front garden. Many would probably do it, but there may be conservation areas or other reasons why the council wouldn't grant permission.
Meh
https://www.independent.co.uk/news/business/analysis-and-features/royal-wedding-family-how-much-uk-economy-benefits-cost-meghan-markle-expense-a8345436.html