Buckle up, you're about to learn something that will blow your mind, and dispel a very common misconception. Or you mind might not be blown, and you might be utterly underwhelmed. However you indicated to desire to learn and understand, so that's a good start.
Most people think that "begging the question" means exposing another more immediate question (or somesuch). What it actually means is relying on an undetermined or false premise as if it were beyond dispute in order to support an equally flawed ultimate premise.
The photos, *as disclosed*, prove approximately two thirds of f*ck all. For reasons we are not privy to, the SCP have taken it upon themselves to crop the data blocks from the photos before sending the remainder to you. The data blocks will contain the record of the approved device, which absent any evidence to the contrary, will be sufficient to prove the speed. Typically the primary speed reading is generated from a doppler radar system, and the second photo taken a known to the SCP and anyone who has the full evidential photos will be to enable the reading to be corroborated based on your average speed by dividing the distance travelled between the photos (they will also know the distance between the dragon's teeth) by the time interval.
You are not entitled to see any of the evidence against you unless and until to reject any and all out of court disposals, and they instigate court proceedings against you. Some forces don't even send photos at this stage as a matter of course, or at all.
You might think that this is unfair, particularly as they have sent you what are essentially the evidential photos with [most of] the evidential bits removed. We are here to advise you regarding the law, not to listen to posters vent about things that we have no control over.
The prosecution do not need to prove to you that you were speeding, they merely need to be able to prove to the satisfaction of the court that you were. If it gets that far, you will get to see the same evidence that the court does, but the relatively inexpensive disposals will be long gone by then.
For 24 in a 20, you should expect to be offered a speed awareness course (which costs about the same as a fixed penalty) if you have not taken such a course for an offence committed within the 3 years prior to this one. And/or you should expect to be offered a fixed penalty (3 points and £100 penalty). The police are quite keen on offering courses, as they get a £35 commission for introducing the customer, and the customers mostly manage to bite their tongues as their primary concern is avoiding the points.
If you ignore/decline the out of court disposal offers, and plead guilty upon receiving the SJPN bundle (usually containing the evidence they would be seeking to rely on), you would expect the same 3 points, a fine based on the magistrates' sentencing guidelines (with 1/3 discount for an early guilty plea) (link in the "READ THIS FIRST" sticky at the top of the speeding forum), a 40% surcharge on that fine and ~£95 prosecution costs.
If it went to trial, and you lost, you would lose the 1/3 discount off the fine and surcharge, and face prosecution costs of ~£650.
Obviously, if you went to trial and won, there would be no fine, no points, no surcharge and no prosecution costs (and you could probably claim your bus fare).
N.B. The above is all based on the assumption that you name yourself as the driver. Failure to do so is a separate and more serious/expensive offence.
Perhaps the most relevant attachment was the calibration certificate - not because being out of date would have helped (it wouldn't), but it shows that it was a RedSpeed camera, not a Gatso - off the top of my head the Gatso BV 24 +AUS is the only approved speed camera whose approval excludes use in limits below 30mph. However, the pattern of the dragon's teeth is wrong for a gatso (or at least highly unusual).
