At Rightmove, we have an automated process that attempts to match sold address data from the Land Registry with Estate Agent listing data, so that website users can see the most recent pictures and images of sold properties that we have access to. That process uses an element of the UK address structure called Delivery Point ID. Sometimes, the government sold price data does not contain a delivery point ID which means we are unable to attempt to match pictures to properties as our process requires that address identifier.  

In addition to this, homeowners can request that their property images are removed which may be why you're unable to see images for some properties, please see more on our removal process here: https://faq.rightmove.co.uk/support/solutions/articles/7000087817-how-do-i-remove-my-sold-house-price-images-