The sponge filter sits in a cage inside the cleaner. You'd only know it was there by taking the cover off the motor, but a cleaner of that style and age would almost certainly have had one.
By 1977 Hoover had an enormous number of cleaners in their UK portfolio - both upright and cylinder- most of which were made in UK, but some -like the Celebrity and Celebrity air-ride- came from other countries. Many models of Hoover did more or less the same as another. Thus, it is not at all surprising to see how the later Constellations had shorter, double-stretch hoses instead of the longer triple-stretch, because as well as saving on production costs, it also gave the whole cleaner more definition in it's own sales line up. That is to say if you wanted a cleaner with more refinement than the Constellation now offered, you'd be drawn towards a model from the Freedom range.
Why Hoover felt the need to offer so much choice, I am really not sure. Electrolux -who were one of Hoovers biggest competitors- never offered the consumer anywhere near as many options; their 1977 range boasted three uprights and four cylinders, each one being designed and marketed in such a way that the consumer could easily see the differences bewteen them and decide accordingly which one had the right features for their needs. So, by the time this Constellation was on sale, it was just another cleaner in a wide range of cleaners, and possibly only still in production because there was some novelty value in its shape.
Having said that, it's worth me saying that this colour of Constellation went on well into the 1980's, with the last models having a rocker switch and beige & brown plastic tool kit. This colour was one which ran for the longest out of all the colours it came in, and yet for me I have seen so few of them.
)
