Why is my beef casserole/stew etc always tough :(

[padboz]

I have tried several ways - cooking at gas mark 1 for 5 hours or putting it on the hob with barely a bubble, or gas mark 2 for 3 hours blah blah. I tend to use skirt or shin from the supermarket. I never have this problem with lamb which is always succulent and lovely - beef is always cuttable with a spoon but stringy - what am I doing wrong???

try a pressure cooker to start then add the veg and cook in the oven .this saves time and money .

The beef's had 5 years to cook, it will be tender by now!!