I always make my tea in a mug. I had occasion recently to take a flask with me for a few days and make tea in the car. Same tea bags as always, same milk. I put boiling water in the flask and made the tea in the cup like I would at home. The tea was delicious and catapulted me right back to my youth and the tea my mum made in her stainless steel tea pot. So I’ve gone today and bought myself a stainless steel tea pot. Brewed it on the hob. But it doesn’t taste like it did from the flask or from my childhood. 
what have I done wrong?