A controller would be a great bonus - yes. But should a controller be REQUIRED? I think not...
Since when do we need full ATC support to shoot an approach. In NZ it works marvellously well to just announce yourself, and follow the procedure. What happens in the UK when controllers become unavailable? Would elf n safety make them go elsewhere? Or would they just follow the procedure and land anyway?
In the case of the monarch flight - as well as a couple more recent incidents, ATC is useful to catch people's mistakes, but surely that is always pilot error is it not? That will always happen, even with ATC!