Just though I'd stick these pictures up in case anyone else was suffering from a reduced flow from one of these smev taps. The end of the tap unscrews and will come apart into four fine mesh filters and a plastic jet assembly. I found lots of limescale trapped between all the filters so a gentle brush with a nailbrush under running water cleared all the scale out and restored full flow. I also took the time to fill our water tank with a Milton mixture and run the sterilised water through the system to kill off any bugs.
We have a similar problem here (and also with shower heads at home). Alter removing the big bits I soak them in clear vinigar, which as a mild acid removes limscale deposits.
