Sainsbury's Red Label loose tea works for us every time in a teapot with a wire mesh tea strainer. The only hassle is emptying the leaves out of the pot but that is because they are saved for the compost bin and that it is nigh impossible to buy an ordinary tea pot with a large unobstructed hole for the spout. Most have a restriction of some sort (perferations maybe) to prevent a teabag from getting into the narrowing spout.
As an aside, years ago when the children were small a friend of our daughter who was round for tea asked whether the tea strainer was for catching the drips!