Discorde - does seem to be missing IAF, DA, and missed approach procedure. I'm not inherently against ad-hoc IAPs, but all of the formality that's there in the official ones is there for good reasons. Turweston is actually an excellent case, as it would readily lend itself to a day-only NPA, certainly GPS, and you might even get away with a VOR/DME approach onto 27 off BKY, and if you mandate ATC - well located where it is that could be provided by either Luton or Cranfield. But there is a lot more to a well designed IAP than simply flying GPS to the runway then landing.
(Also if you were in the vicinity desperate to land from above 8/8 you of course have multiple approaches at Cranfield, and if you're out of hours, can just apologise later after a safe landing!)
Fl1ingFrog - if you look up the dreadful mess made of the implementation of the IAP at Sywell, including correspondence from the airport accusing the CAA of trying to actively prevent it having any utility whatsoever (which they largely succeeded in achieving): the whole lot is online at the link below - you'll easily see where all the time and money went. The position isn't faintly defensible, but it's what it is has been to date.
https://www.caa.co.uk/Commercial-ind...al-procedures/
G