what was said on the bbc ( and uncontested) ....was that someone/folks have come up with a figure of ?143 billion of tax owed to the treasury.....   that might make a difference to the overall financial situation....

Could you find a source for that sum, ecu?  If it is true, that is almost twice the sum the last Government spent propping up the banks (and would it be their 'activities' you were referring to?).  From what I understand, the hole in the national pocket is somewhere between 600 and 700 billion; whilst 143 billion would go nicely towards helping clear that, Labour's insistence that the while problem is down to the global economic crisis seems a bit thin when one asks where the other 500 billion or so has gone?

there was though a question of ... the political indulgence of not sorting out the loopholes

People have been pushing the politicians to close these loopholes for 15 or 20 years.  There was no political appetite for doing so under Blair or Brown; why does the Tory/Lib Dem coalition suddenly get lambasted for not doing so?  It is partly this hypocrisy that has Labour - in one breath - not just failing but, in some cases, point-blank refusing to act on this and other things and then, in the next, accusing their successors in power of pandering to the rich.