A summons for speeding (and other offences) must be issued by the Magistrates Court within 6 months of the date of the offence. For the case to have got this far the prosecutor must have served a Notice of Intended Prosecution (NIP) within 14 days of the offence and properly identified the driver.
The summons must also comply with requirements relating to both time of issue and content. For example it must clearly and correctly state the speed limit alleged to have been contravened, identifying whether the road was "restricted" or not. A road becomes "restricted" and subject to a speed limit if its street lighting is not more than 200 yards apart OR the relevant local authority makes an order that it should be restricted.
Sometimes these need checking. It is not unknown for a summons to allege speeding on a restricted road, when the road is not in fact restricted.
If all procedural and content requirements have been complied with, the case then becomes one of evidence; in other words the question is whether the evidence obtained by the speed detection equipment is adequate to lead to a conviction.