I'd like to substitute sherry for the worcestshire in this recipe. Can you advise how much to use, when, and if I would also eliminate the lemon...

Also keep in mind that by removing the Worcestershire sauce you are removing salt (whether a benefit or a loss in your eyes). So, be sure and check the seasoning in case this sherry-revised version needs adjustment just before serving.

2 TB sherry, and definitely leave out the lemon juice. You can use rosemary or not, depending on what you like. Thyme is nice, too.

I think I would go with ~2 tablespoons as suggested in the headnote, and probably add in step 4, allowing to simmer a little, then proceed as written (I'd leave out the lemon juice; personally I'm not a fan of rosemary so I myself would leave that out, it's delicately flavored anyway given the mushrooms and artichokes so you don't want to overpower those ingredients). Maybe Barbara can weigh in regarding the original recipe.