Tea Makers of London for me too for the past 20 years. I only have a pinch in each mug, so it takes me a year or so to get through each tin. I bought in bulk last time, so my current tin says BB 2018. But, tastes fine to me. I should add that I'm no connoisseur.
P.S. Sorry, I'm talking Jasmine Tea. Just noticed you're talking Green Tea. So, ignore me.