Agree with the above....The rules are a bit of a grey area....I'll ask those in the know in the AM..in the meantime:
If you read the transec/DfT sites you'll see it is open to interpretation as to whether it is open to interpretation...but I do know that when the liquids ban kicked off security were confiscating liquids containers with a volume of more than 100 ml, regardless of whether they were full, partially full or empty. I think the rules have relaxed a bit recently but chapter and verse is here:
https://www.gov.uk/hand-luggage-restrictions/overview
Liquids in containers larger than 100ml generally can’t go through security even if the container is only part full. There are some exemptions.