It would help drive up food safety standards across the industry by making good hygiene an integral part of an organisation's culture, said Watkinson.
Her views are echoed by others, including food consultant Dr Jo Head who, talking about the trend for unannounced audits, said: "I think it is a pressure that is going to be increasing in the next few years."
Watkinson said: "Unannounced audits can only be a good thing. It means the operations; the plant and factory have to live their values every day."
Some retailer-led audits of suppliers, such as the Tesco Food Manufacturing Standard, are unannounced. However, third-party audits carried out by certification bodies to schemes such as the British Retail Consortium (BRC) Global Standard are mainly by prior arrangement.
Under version six of the BRC standard introduced at the beginning of 2012, changes were made allowing suppliers to opt for components of the audit to be unannounced. Either the whole audit could be unannounced or the factory inspection part could be unannounced and the part dealing with assessment of documentation announced.
"For companies that want to dip their toes in the water it is absolutely a good opportunity," said Watkinson. "But it would have been good to see BRC go the whole hog this time." She reckoned when the next version of the BRC's standard was published in three or four years' time unannounced audits would be the norm.
Watkinson said in her opinion the consistency of BRC audits were improving both from a viewpoint of auditor competence and the type of non-conformities raised. "That is really important for the standard to survive," she added.
She also argued that the Food Hygiene Rating Scheme (FHRS) previously known as 'Scores on Doors' should be made compulsory, because this would also drive up standards.
The FHRS was developed for catering outlets by the Food Standards Agency. It is expected to be taken up by about 99% of local authorities across the UK by the end of 2012. However, foodservice outlets are not obliged to display the scores if they are poor.
"The Welsh Assembly is looking at [making it compulsory], she said. "If they do, they will have to roll this out. By 2013, it would be great to see that in place as compulsory."