Land Registry
HM Land Registry is the government body responsible for registering ownership of land and property in England and Wales. Every change of ownership must be registered, and all registered titles are publicly searchable (for a small fee).
For property investors, Land Registry data is an essential research tool. The sold prices database (searchable free at gov.uk/search-house-prices) shows every completed sale with the address, price, date, and property type. This is the most reliable source of comparable sales evidence for any property in England or Wales.
Land Registry data lags by approximately 2-4 months from completion date to appearance in the online database. Very recent sales may not yet be visible. For the most recent transactions, Rightmove and Zoopla's sold price data (which sometimes appears earlier) can supplement Land Registry.
The title register for any specific property can be downloaded from Land Registry for £3. This shows the registered owner, any charges (mortgages) against the property, and any registered covenants or easements. Downloading the title register before making an offer on a property can reveal useful information about ownership history and any encumbrances.