There are a couple of preludes that are definately above the DipABRSM. For some that'd fit at that level, I'd say these ones: C major, G major, D major, E major, C# minor, B major, G# minor, F# major, Eb minor, Ab major, F minor, Bb major, G minor, F major.
The ones that'd sound really good together, and would contrast with eachother (and aren't the super overplayed ones)... E major, C# minor, F# major, Eb minor. I really don't know; you might have to call the 'place' where they do the repertoire for the level, make sure you know which you are allowed to play... there's a couple that are clearly below, like E minor and A major, and the Bb-, Eb+ are probably a bit higher

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