It's amazing how something so simple as double cream can just make the dish! You can obviously use fresh salmon if you like, it was just convenient for me at the time to use a tin ;-)
If you're good with your timings, you can boil the potatoes, broccoli and mushrooms all in the same pot to save on washing up :-) Just add the broccoli in the last 10, and the mushrooms in the last 5 minutes of your potatoes being done.
I say it serves 2 people, but I'm quite greedy so it could probably serve 4 (small) dinner portions with a side of extra veg.
http://hungryjenny.blogspot.com/2010/08/friday-pie-day-accidental-salmon-pie.html