Seems like you'd need to prove the pills in question were the alleged substance?
Just linking a picture of alleged narcotics to someone via their fingerprint doesn't seem like it should rise to the level of reasonable suspicion. I don't know what the standards are for the UK though, so I may be applying assumptions.
His sentence in the end was for conspiracy to supply cannabis. The suspicion to search was contextual, given that the image was obtained from another arrested person (presumably for a drug offence) along with other messages implying he was dealing to them, such as "what do you want to buy?".
Although I'm not sure how the fingerprint comes into this, given that they didn't find him by it, but rather "officers had an idea who they believed was behind the drugs operation", and he was convicted of a different crime, with evidence from his home search.
I don't think the pills matter. I think someone was caught with drugs, said "Here's the whatsapp conversation I had with the person that sent them to me" and received the fingerprint. I think they already had the drugs.
Just linking a picture of alleged narcotics to someone via their fingerprint doesn't seem like it should rise to the level of reasonable suspicion. I don't know what the standards are for the UK though, so I may be applying assumptions.