Sadly this is a decimated series, with only three of the seven episodes available, the other four lost along with so many other gems, such as Doctor Who and Dad's Army.
Horror was definitely popular in terms of Television Serials in the Seventies. Dead of Night is a little known series, overshadowed by the likes of Tales of the Unexpected, Ghost story for Christmas and Thriller. However this series has so much to offer, from the three stories you get a decent flavour for what the remaining episodes will be like. Exorcism is easily the best of the trio, it's dark, imaginative, well acted, featuring several ghostly scenes.
Some names of real quality were behind this series, the likes of Robert Holmes, Ines Lloyd and Louis Marks, names any Doctor Who fan will of course be familiar with. From what I've seen, the production values and acting are excellent, the quality of writing does vary however.
Let's hope the remaining four are uncovered one day. 8/10