Hundreds of people joined former defence minister Johnny Mercer in a London march to support veterans.
A rally of bikers from campaign group Rolling Thunder UK, which organised the event, were among those at Parliament Square in central London on Saturday.
They rode in their droves into the capital and assembled close to the statue of Sir Winston Churchill outside Parliament as demonstrators waved flags and brandished placards, with one banner saying “stop vexatious trials of vets”.
A crowd gathered as Mr Mercer was joined on stage by British soldier Dennis Hutchings to give a speech.
It comes after two former paratroopers accused of the murder of an Official IRA leader were formally acquitted at Belfast Crown Court after prosecutors offered no further evidence at their trial.
Mr Mercer has previously called on the Government to include veterans who served in Northern Ireland in a new Bill to protect soldiers from prosecutions.
The former Army officer left the Government last month after it emerged the Overseas Operations Act would not include soldiers who served in Northern Ireland.
Speaking after the demonstration, Mr Mercer said: “Today’s march was about demonstrating the strength of feeling on the issues of veterans’ affairs.
“The country has always got it, Government never has, and that has to change.
“I was delighted at the turnout at such little notice. Thanks to everyone who came out.
“We’ll be watching the Queen’s Speech closely for the promised legislation.”
In his resignation letter, he said he had “no choice” but to leave after frustration at a lack of progress over the legislation to protect British veterans who served during the Troubles.
He said he had hoped Mr Johnson’s premiership would “signal a step change in veterans affairs in the UK” and that he had raised his concerns in a face-to-face meeting with him.
The legislation, which gained royal assent in Parliament last week, was developed in response to legal claims made after operations in Iraq and Afghanistan.
The Overseas Operations Act will come into effect following the opening of the new Parliament on Tuesday.