Flatworms, Tapeworms, Flukes, etc.
Set of videos by High Jones covering various species, including at least two (Microplana kwiskea and the 'Southampton flatworm' cf. Caenoplana bicolor) that are new to Britain since Hugh's 2005 identification guide.
ID sheet on non-native flatworms from Non-Native Species Secretariat.
Jones, H.D. 2005. Identification: British land flatworms. British Wildlife 16(3): 189-194. [A few species have been added to the British list since this was published.]