PropertyData's Plot Map is a straightforward and quick way to determine the title number of any plot of land in England or Wales.
Start by entering a full postcode (or co-ordinates or a what3words address) in the Plot Map tool:
Once the Plot Map loads, there may be a quick wait while the land title outlines load (a progress bar is shown on the top left).
When the titles have loaded, hover over the plot of interest to confirm its boundaries. If the lines are blue, that means it's privately owned – orange means onshore corporate ownership, while yellow means offshore corporate.
Click the plot you are interested in, and the title explorer will appear on the right of the screen.
Lots of useful information is shown here, including the official Land Registry title number.
If the land title contains more than one parcel, the others will have been highlighted when you click the first one, and additionally the area field in the title explorer will have an 'i' icon which you can click to see a breakdown of the parcels and their ID: