Maybe I'm missing something but tax minimisation isn't illegal and many expax/offshore contractors know a good company who can do this for them, not just the SME or globals.
Tax Evasion is illegal and nobody would claim otherwise.
Contractors, SMEs and corporations are usually very careful about which side of the line they operate on and do everything legally but for their own best interests. The primary interest being keeping as much of the money they get as possible.
Obviously global corporations can afford whole departments to move things around, stay within the laws and minimise their taxes. Whether it's morally right or wrong seems a strange objection when they are not breaking any laws.
Legally many government ministers didn't break any laws, morally and ethically their decisions were questionable, but as they tried to defend 'it was within the rules'
If the UK government wants to stop the losses then sort the laws/legislation out. Trying to stir up ill feeling against corporations because they use the rules to their own advantages to minimise their tax, rather than fixing the rules to make it harder for them to do seems like nothing more than 'we need to appear to be doing something'
Regardless of whether people think it's morally right/wrong or distasteful... how can you attack someone for knowing and using the rules to their own advantage...
How many people, including the government, would honestly do any different?