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Thanks guys for the help, I had an indirect response from the slug guy at Liverpool Museum who has investigated the invertebrates in the Anglican Gardens. He agrees that the large grey mottled ones are Limax maculatus (= Limax pseudoflavus).

Thanks Bugbotherer for the suggestions for the other two. They were both only an inch or so. Neither 'woke up' so I wasn't sure of tentacle colour.