There should be plenty of episodes for any television show on the internet which you can watch for free, and it's not usually illegal either. You could try www.youtube.com and search there, but you may find you have to watch episodes in two or three parts. Some websites such as www.ovguide.com use the youtube videos: You watch the episodes from youtube but on the OV (Online Video) Guide website. This kind of site needs no sign up, download or payments, but the quality might not always be the best. Other sites may require you to sign up and create an account with them. Whilst many sites like this are indeed safe to use, there may be a catch to some of them. Most sites like this will ask for your email address when you sign up which could mean you end up with lots of unwanted junk mail; some may ask for your credit card details, even if they claim to be free sites, which is obviously risky to give out. Another idea is to go to the official Midsomer Murders website: Www.itv.com/midsomermurders. Here there are clips and information, plus you can go to the ITV Player and watch any episodes that have been played on TV recently.
You can try veoh.com. This is a free website and it is legal. I love my stargate series and all my sci-fi movies are in here, when my children or husband gets the tv I always go to veoh.com to watch what ever I want.
Stage vu has several episoides of season 12 - UK season. Use the advance search - submitted by Inga. You do need to download the DivX player. It is quite quick, although the buffering time is not.