England being choked by Foreign Invaders

No, not a piece out of UKIP nor BNP more Kew Gardens..
I know Australia has a similar problem with 'Patterson Curse" that it is solving with an insect from the South of France. However I also seem to remember that previous 'solutions' like this have created issues of their own - Foxes for Rabbits in Australia springs to mind.
http://news.bbc.co.uk/2/hi/science/nature/8555378.stm
There are plenty of others waiting to take over from the Japanese knotweed should that problem be resolved though.

They are pennywort, New Zealand pigmyweed, water-primrose, parrot's feather and water fern

http://news.bbc.co.uk/2/hi/science/nature/8534567.stm
But maybe we are starting to step on the toes of the formerly mentioned political parties if we go down that route..

Let's hope the British Govt don't make the same mistake they did in Oz with this little bugger.....http://www.stopthetoad.org.au/

There have been a few successes In Oz, including the one you mention, and various varieties of dung beetle to control the cow sh1t, thus cutting down on the fly population, and making the cow pastures more habitable.

Less successful were the cane toad (as mentioned by Aa), and foxes and rabbits of course.

The jury is still out on the occupants of the following vessels:

H.M.S. Sirius
H.M.S. Supply
The Fishburn
The Borrowdale
The Golden Grove
Alexander
Charlotte
Lady Penrhyn
Friendship
Prince of Wales
Scarborough