Just did this. I ordered madras from the source noted earlier in cut lengths for shirts. Decided to wash ahead of sending to tailor. Threw the 2 non-bleeding in the washing machine with the one bleeding they offered at that time (sounds like it might still be available) and used hot water. When they came out they all looked pretty much the same. That said, the bleeding version is a relatively muted colour scheme which has a cream background and the other non-bleeding colours I ordered were much bolder. I may have ruined the bleeding effect by running through the dryer but the fabric is a relatively loose weave and I was afraid of post-tailoring shrinkage. I still hope for some bleeding effect but only time will tell now. Maybe these fabrics just don;t bleed as much as before.
Perhaps a lukewarm soak instead? If you put it in a basin, you would get some insight into how it bleeds.
Did you get all of those samples from www.scotlandshop.com? I've been looking for a brown POW like in your photo and when I sent Lovat an e-mail a couple of months back, they said they didn't have anything similar in stock.