Posted: 30/08/2015 at 14:43
We have Spanish slugs here too - they are voracious - I get rid of them.
The John Innes Centre (a mile up the road from here) is doing a lot of research locally into slugs and they have a very good ID chart here http://www.slugwatch.co.uk/?page_id=21
Superficially a Spanish Slug might be mistaken for an Arion Rufus as it could be described as orange-ish , but the Spanish Slug is a muddy brownish orange, whereas Arion Rufus is a bright orange.
Was the one on your kniphofia really this colour Verdun?
or was it more like the ones here?