An inoffensive worm? More...

Flatworms (Platyhelminthes) are simple organisms that lack specialised circulatory or respiratory systems. This group includes  parasites such as tapeworms and flukes, but there are also free-living flatworms that are found in soil, leaf litter and water. There are approximately 21 species of land flatworms in Britain, only four of which are native. Kontikia ventrolineata is a non-native species originally from Australia and New Zealand but is thought to have been in the UK since 1840. It has just joined a growing list of flatworms which have been spotted in local gardens. K. ventrolineata consumes any invertebrate it can catch, especially snails and slugs.  

Because of their potential impact to populations of earthworms and other soil animals, all non-native flatworms are included under schedule 9 of the Wildlife and Countryside Act 1981, which states that it is an offence to introduce or release them into the wild. Given the length of time this inoffensive species has been lurking in britain and how rarely it is seen, it doesn't seem that there is too much to worry about.