From 1 July 2020, INSPIRE spatial polygon datasets which map more than 23 million title extents across England, Wales and Scotland have been available on the Use land and property data service and Registers of Scotland’s website. The data shows land ownership boundaries for England, Wales and Scotland.
Until then, this data has been closed and couldn't be reproduced publicly - the public wasn't able to see maps of land boundaries across the UK, nor could journalists easily use it to investigate.
Most of the data is free to access but you may need to create an account and sign a licence agreement first.
You can check out and download the datasets here: https://use-land-property-data.service.gov.uk/#ips
Keywords: England, Wales, Scotland, UK, land ownership, land ownership boundaries, property, UK House Price Index, spatial data, company land ownership data, price paid data, registered leases