I've taken 100ml Eros {Which is Pjur*} lube through Luton airport a few times
and Eros 30ml every single time. Some with labels, some without.
If they looked and asked, I'd say:
"It's sex lube; that's ok, yes?"I never
ever put anything in a clear plastic bag and I always deny
having any liquids, cosmetics, underwear, false teeth, bowls of Weetabix,
or whatever else is the pretend threat of the week. It's all security theatre.
Plus, the queues for security checks are a perfect target for a bomb
or machine gun attack. The people who make these rules are donkeys.
Not bad people, just donkeys.
I've only had my bag checked once. For an pack of AA batteries
which looked weird from the angle the x-ray. They were fine with
that. Though the 65 year old WI lady from Henley, who was having her
handbag checked for AK mags and claymores, was less impressed with
me while we waited and I pointed out that these checks do zero for safety,
have never stopped an attack and actually put us all at far greater risk
of attack. And resources are better placed with profiling, more Armed Air
marshals and Intel ops which stop the attacks before they get to the airport.
Her mood lightened when she realised we didn't have adjacent seats.

In Luton duty free you can freely purchess heavy bottles of whiskey,
sets of steak knives and probably Anti tank mines too

, without trouble.
All these would make excellent weapons on an aircraft. as would the
In Flight Duty Free magazine, if tightly rolled up.

If they cared about security, they'd ban all glass bottles and ban all alcohol
drink sales on board. But they won't coz they don't really care. Least wise,
not above making money.
...Sorry, what was the question?

Oh yes, you were within the set rules. But final discretion lay with the staff
at the security checkpoints. Which is reasonable, to a degree. I suggest you
write in to Luton Airport security and take their reply with you next time.
On a positive note from all these niggles. We can now travel at over 500mph
at 36,000 feet across continents while having a cuppa and a Mars bar.
Which is pretty awesome when you think about it.
*Edit
Eros & Pjur are the same lube, same bottles. Made in the same factory.