To ask the Solicitor-General how many cases were discontinued by the Crown Prosecution Service at (a) committal and (b) a later stage for reasons of (i) a lack of preparation and (ii) delay in each of the last five years; and how many cases were dismissed by (A) magistrates courts and (B) Crown courts for those reasons in each of those five years. 
Cases are rarely discontinued at committal for reasons of lack of preparation or delay. If a committal is not ready, the CPS tends to seek an adjournment to enable the file preparation to be completed. If the adjournment is not granted, the CPS will have to offer no evidence and the committal is 'discharged'.
Table A shows all reasons for which cases were discharged at committal during the four years for which data available. Each applicable reason is also expressed as a proportion of all completed cases in magistrates courts. Table B shows the reasons for which case were dropped in the Crown court following committal for trial, both by volume and as a proportion of completed Crown court cases.
No comparable analysis is maintained of the reasons why cases result in dismissal by the magistrates or acquittal by the jury, as these outcomes are the decision of the court rather than of the prosecution.
Proceedings for an offence that has been discharged at committal because the prosecution is unable to proceed may be re-instituted. After a committal has been discharged, the prosecutor will liaise with the police to consider whether the proceedings can be re-instituted.