Do sub-250g drones need registration in the UK?

Yes, most sub-250g drones require drone registration in the UK.

The requirements are:

Flyer IDOperator ID100g to less than 250g, with a cameraRequiredRequired100g to less than 250g, without a cameraRequiredOptionalLess than 100gRecommendedOptional

For more details on Flyer ID and Operator ID, click here.