Where is the Eurostar lounge in St Pancras? It took me 5 good minutes to find it, and I realized other people had the same problem. In fact, access to the Eurostar lounge in St Pancras is just on the right as you exit from passport check from the Business Premier priority gates (the ones on your right when you walk towards check-in in St Pancras). After passport check, you will notice a relatively small sign on the right, and a desk with an agent.
But if you arrive from a normal check-in gate, you have to walk past passport controls, turn right around a glass wall that separates the priority check-in area from the common mortals, and you’ll notice the small sign – now on your lefthand side.
Access to the Eurostar lounge is granted if you have a Business Premier or Leisure Select ticket, or a Carte Blanche.
You should not be able to access the lounge on a Leisure Select (or as it now called Standard Premier). I had to travel for about 2 months on LS tickets before I got the card, then I got in.