This is one of those things that continues to elude me, and that I'd like to learn good technique for doing.
What I usually try is:
Once the meat (be it beef, lamb, pork, venison, etc.) is cooked, remove the roast from the oven. Take it out of the roasting pan. Skim off clear fat but leave any that has any colour or cloudiness to it, as well as a thin amount of the clear fat as well. Put the pan on the hob at a medium-high heat. Then, add (white, usually low-protein) flour. Use enough to absorb the remaining drippings, and form a smooth paste. Spread over the surface of the roasting pan and (attempt to) cook. At a certain point, add (hot) stock gradually, stirring all the time, and continue cooking so that you get something slightly thick. When finished pour into the gravy boat.
What goes wrong:
1) I never seem to be able to get a good dark gravy. My expectation is that it should be a VERY dark, burnt-umber brown with perhaps a tinge of reddish. Instead, the colour is usually at best dark tan.
2) The gravy always lumps, and the lumps can't be got rid of. It doesn't matter how much stock is added at any one time. If I add a lot, I get lumping from the paste. If I try to add a very small amount, it just boils away before the gravy can be formed and I end up with a paste again, albeit flavoured with a reduced stock in addition.
I'm told on the one hand that it should be possible to brown the roux. I've never noticed this. No matter how high the heat, or how long I stir, it doesn't brown; it merely seems to dry and become powdery while remaining pale.
I'm also told that using hot stock should prevent lumping. This is definitely not my experience. Hot, cold, lukewarm, it seems to make no difference. I get lumps every time. I've also tried various different types of flour, with various protein contents and milling finenesses, all to no better effect.
Interestingly, poultry gravy seems to present few problems for me, but perhaps that's because a paler, thicker gravy is usually desirable in that case.
Can anyone diagnose from what I've given as the symptoms what I might be doing wrong? I'd also like to say, please, I'm not particularly interested in "short cuts" or "tricks" such as the use of "secret" ingredients, special equipment or tools, very unusual technique given without explanation as "it works every time...", or enhancers used to improve gravy. I really do want to learn good fundamental technique here. In principle it sounds as though it should be simple but it seems clear I'm doing something very wrong (maybe in fact my entire approach is faulty, for that matter).