David Heathcoat-Amory, the Shadow Treasury minister, is demanding to be told why it has taken so long to investigate undeclared directorships of a number of companies, including one that was part of Robert Maxwell's business empire.
He wrote to Sir Gordon, the Parliamentary Commissioner for Standards, on 17 February asking him to investigate the commercial interests of Mr Robinson that had not been declared in the Register of MPs Interests. Shadow Chancellor Peter Lilley has made similar allegations.
Now Mr Heathcoat-Amory has written again, asking for the reasons for the "apparent delay" in the Commissioner's investigation.
"Prevarication may suit Mr Robinson, but I am sure you would agree that these matters should be investigated and reported as quickly as possible," he says. "It is now nearly three months since I first drew your attention to the breach of rules."
He points out that when allegations were made against the Labour MP Bob Wareing, the Commissioner's investigation was completed within a month.
"I would be grateful if you could tell me how your inquiries are progressing, if you have met any obstruction and when you hope to report your findings." asks Mr Heathcoat-Amory.
However, senior government sources yesterday suggested that Sir Gordon would not delve any further into Mr Robinson's past business life, on the grounds that the Commissioner would be overwhelmed with work if he was obliged to investigate every undeclared interest going back over the last two decades.
The Conservatives have submitted details of Mr Robinson's chairmanship and emoluments from Agie UK Ltd over a number of years before they were finally registered in December 1987, and of his chairmanship of Hollis Industries plc, where he was paid pounds 200,000.Reuse content