I'm convinced that Satanic Rites of Dracula was a rewritten Pertwee serial.
Probably, as it was by Don Houghton.
Still the merging of that style with vampire fiction ended up being very original.
Satanic Rites of Dracula is really a template for the likes of Buffy, Supernatural, Blade, Being Human and Angel. I'm not saying they were all inspired by it. In fact probably only Being Human was, but it was doing things they were decades earlier, and should get the credit at least for being ahead of its time that way, but ironically it gets mocked for all those things!
Let's see.
A line of vampire hunters that stretches back through the ages, the latest of whom are a young woman and a crusty old English guy. This movie and its forebear, Dracula AD !972 were the first movies to feature a Van Helsing family, which would not only become a stable of other versions of that character, but again inspire other lineages of vampire hunters, either families or chosen ones like the Slayers and the Winchesters. Similarly these lineages are often represented by a crusty old guy and a young woman, from Quincy Harker and Rachel Van Helsing, to Mary Winchester and her father, to finally Buffy and Giles.
A vampire, or supernatural creature that in the modern day poses as the head of a company, and uses his connections and wealth and status as a big shot to cover up killings and gain access to victims and has human servants running around with guns? Not at all like Wolfram and Hart, the Mayor, vampire kings like Herrick in Being Human, the vampire nation in Blade etc. D D Denham is the precursor to all of them. He wasn't a vampire who skulked around in an old crypt, or was just a weird nobleman who went after someone he was in love with and was easily hunted. He was fully integrated and protected by the law and had member the elite dancing to his every whim. He also served as a frightening metaphor for how predators can escape justice at the top of the society, not just through their connections, but also because people often don't care about their victims. IE these young women who are viewed as easy slappers asking for it, and who go on the missing persons list quietly with no one giving a shit.
We see all of these things pop up with the Mayor, with the Wolfram and Hart, even Russell Winters the first villain in Angel, is basically just D D Denham again.
An ancient vampire that plans to bring about the apocalypse in modern day. Lot's of people rip on the movie for this, saying it's absurd, but it's not. To start with it's made clear that Dracula does not want to live anymore. He wants to kill himself, but fittingly rather than just go quietly into the night, a creature of evil and hate like him wants to go out in one last blaze of glory.
Second the idea of a vampire or a demon wanting to destroy the world, or bring about armaggeddon is again something we have seen in Buffy, Blade, Supernatural, Angel, Being Human dozens of times. All of those series are praised, yet this one gets singled out as being so ridiculous for that reason? Some of their end of the world scenario's make even less sense. Look at Buffy season 2 finale? Angel's plane makes no sense. That's still a classic story for other reasons, but still his basic plan is far more nonsensical than Dracula's.
Similarly the idea of a vampire using modern technology to destroy the world, rather than ancient spells is also inspired and something that pops up in all of these modern day, more respected works. It's a scary thought that things that we think are making our lives better are actually making it easier for the monsters to prey on us. Examples of this include the Crocotta in Supernatural, a monster that can imitate people's voices and in the olden days hid in the bushes and lured people out with calls, but in the modern day can use phones to lure people to remote locations, or the vampires in Blade using genetic engineering to remove their weaknesses, or the Master in Buffy using a machine that drains people's blood out in the Wishverse.
D. D. Denham using chemical war fare to bring about the ending of the world, rather than a dark spell, is again really the forebear to that type of story.
Similarly Legend of the 7 Golden Vampires, was the first to really merge the vampire and kung fu genres together, and it also was one of the first to play around with the idea of all vampire myths being true, and it also was the first to touch on Chinese myths about the Jiang Shi.
Not long after it was made in Hong Kong there would be an entire sub genre of kung fu vampire films based on the Jiang Shi myths, that would be huge over there. They would feature a character called "Mr Vampire" who was conceived as being an Eastern Van Helsing. He was played by the late great Lam Ching Ying, who was also marketed as Hong Kong's answer to Peter Cushing. One of the Mr Vampire movies was even directly inspired by Legend. It's plot sees Mr Vampire tackle Dracula, and similarly be out of his depth against the western vampire in much the same way as Cushing was against the Chinese vamps. It was even conceived as a loose sequel to Legend, hence why Dracula's body is found in China!
Following the success of the Mr Vampire movies, western vampire series would start featuring kung fu vampire films too, like Blade, Buffy, etc.
Yet in spite of all this, Hammer fans ALWAYS trash Satanic Rites as being the weakest, and Legend not far behind and again they trash them for these reasons! "Oh having Dracula want to end the world was silly, kung fu vampires is desperate." Mark Gatiss in particular said that Legend of the 7 Golden Vampires is so bad, there is no way you can defend it, and laughed at it for having Kung Fu Vampires.
Yeah Gatiss, you're right, Kung fu vampires was a total dead end in that genre.
I can't think of ANY significant vampire films or tv series that went in that direction?
Now again this doesn't mean you have to like those two movies, but at the very least they should get credit for being ahead of their time. Far more so than sequels like Dracula Has Risen From the Grave or Taste the Blood of Dracula.
Sadly however once again as these movies came out when Hammer was on its last legs, and no longer thought of as cool, then I feel that fans like Gatiss assume they must have been the worst and trash them more severely, and subsequent generations go into them with a bad attitude and much like Lost in Space they don't get the credit they deserve.
To be fair I also blame Christopher Lee. He always slagged off Satanic Rites. Sadly as seen with True Who, when you do that, you always end up being seen as poorer. Nigel Kneale is hailed as the father of sci fi on tv, despite very little taking from him, because he bummed about himself. Never be self depricating in the entertainment industry.