You also get an unintentionally-biased response from the USA, where you can't import real haggis, but can buy canned abominations that have little to do with the original dish. They are often made with beef, for a start, which is plain wrong.
The commercially aggressive approach by MacSween, however, has made a very decent haggis available in a huge range of shops across the UK, which wasn't the case as recently as 10 years ago. I bought the one I ate last night from a mini-Waitrose, which is their equivalent of a Tesco Metro or a Sainsbury's Local - shops which often frustrate because of their limited stock. This branch had both haggis and vegetarian haggis in their stripped-down product range.
There was a bit left over, which is forming the middle layer of tonight's pigeon pie. Let's see how that works...