Last time I travelled on Jet 2 years back to Bkk duty free shop at Heathrow would not sell me any booze as changing at Mumbai, they said they would not let you through with it. At Mumbai there is a duty free area and I noticed people had drinks they had bought there taken away at the gate as 'no security tags'. Anyone know what the situation is for this now?

Still the same, IME.

But try asking, just in case !

Security for transit-passengers at BOM (or indeed DEL) remains the same friendly caring service & attitude.

And the duty-free prices, in Mumbai's brand-new terminal-2, seemed to have gone up, when I passed-through a few months back, by-the-way !

Best bet is to buy duty-free when you arrive in Bangkok. Prices are better than Heathrow in my experience although the choice is more limited.

People moan about Mumbai but I always found it OK and have no objections to security checks to foil possible threats from the religion of peace. I thought Bkk duty free was hardly cheaper than Tesco in Bkk?

Just to add, after re-reading the OP, I've never known D/F bought at Mumbai to be taken away, when boarding at the gate.

The security can see from the receipt & sealed-bag that it's just been purchased, inside their terminal, so shouldn't need one of their tags.