The Campaign to Protect Rural England (CPRE) has spoken out today in favour of a blanket 30mph speed limit in all villages. Apparently most county councils have failed to do this, and some villages even have 60mph limits through them. This is probably due largely to the considerable expense in introducing or modifying speed limits. The CPRE's suggestion is for an amendment to the Road Safety Bill so that there is no need for councils to take any action.
It won't be as simple as that, as contradictory road signs (40mph signs within a village, for example) would need to be replaced or taken down. I would also think that 30mph signs would still need to be placed at all entry points anyway, to remind drivers of the legal speed limit. Nonetheless, it's a laudable initiative.