Mr Nelson was drawn into "arms for Iraq" territory at Question Time by Labour backbencher Denis MacShane, who saw an opportunity to get in on the big story during exchanges on the Overseas Trade Service.
"Can Mr Nelson give a guarantee on overseas trade that no minister will be signing any certificates that could send innocent British people to prison in order to promote the interests of MI5?" Mr MacShane asked.
The signing by ministers of public interest immunity certificates to prevent documents being released in the abortive Matrix Churchill trial was a central part of Sir Richard Scott's inquiry.
But Mr Nelson said he could give the assurance the Rotherham MP sought. "It has been the case that has obtained up to now and it will be in the future. As the minister in my department responsible for the export control of weapons, we take those responsibilities extremely seriously. We are not above learning from experience, but we intend to fulfil our national and international obligations under the law."
Mr Nelson was happy to oblige Harold Elletson, Tory MP for Blackpool North, who urged him to condemn Labour MPs "who spend their political lives undermining defence exports and defence jobs".
If the Government listened to Labour MPs, just about every British export market would be closed down, Mr Nelson said. Supplying equipment to enable countries to defend themselves was wholly legitimate and provided "millions of jobs in constituencies represented by Labour MPs - though sometimes you would never think so".
A call to shelve plans to switch MI5 officers from anti-terrorism to fight organised crime was given short shrift as MPs completed work on the Security Service Bill.
Suggesting the Bill should not proceed in the aftermath of the Docklands bombing, Alan Beith, the Liberal Democrat home affairs spokesman said it would be a clear signal to the terrorists that there would be no let up in the security and intelligence effort directed against them. It would be "unwise" to think what happened on Friday was a one-off, Mr Beith said.
But Home Office minister David Maclean disagreed. Dropping the Bill would send a signal that "the IRA commanded the agenda of this House rather than elected members", Mr Maclean said.Reuse content