The now "traditional" long running "Peace Camp" protestors permanently encamped in Parliament Square led by Brian Haw, has been swelled in recent weeks by Tamil demonstrators,protesting about the humanitarian crisis involving the thousands of trapped civilians in the Tamil Tigers versus Sri Lankan government combat zone.
What they really expect the British Government to actually do about this situation is unclear, in spite of the hunger strikes which some of them are now on.
The Police seem to have penned these protestors in on Parliament Square Gardens, with lots of barriers etc. and the annual London Marathon race does not seem to have been affected.
The largest Tamil demonstrations were when Parliament came back from Yet Another of their recesses at Easter, when the road between the Palace of Westminster and Westminster Abbey was blocked by thousands of protestors sitting down peacefully.
This demonstration was not an authorised one under SOCPA Designated Area but there seem to have been few arrests under that legislation.
The fact that Parliament continued business as normal, with no problems for MPs or Peers being able to attend, (they do, after all, have underground tunnel access to the building from Westminster Tube station and from Portcullis House) also shows that the "sessional orders" and indeed the SOCPA section 132-138 Designated Area is far too widely drawn, over far too large an area, to be justified on the grounds of protecting access to Parliament.