Thousands of members of the Orange Order are marching through Edinburgh today in a bid to persuade waverers to reserve the union and vote "No" in Thursday's referendum on Scotland's future. Organisers estimated 10,000 would attend but "Yes" campaigners have put the total at closer to 3,500.

Orange Order chapters from Northern Ireland including Belfast, Antrim and Londonderry will also be on the march, with organisers stressing it will be a peaceful affair and only full members of the Order can take part. Liverpool's Provincial Grand Orange Lodge is also participating.

The Scottish Orange Order's grand treasurer, James MacLean, said: "We have worked very closely with Edinburgh City Council and Police Scotland to ensure that we have a trouble-free march and that the undoubted inconvenience is kept to an absolute minimum."

"The 'No' campaign has been criticised for not showing enough passion for the Union," Scotland's Orange Order grand master Henry Dunbar told marchers, "well look out, here comes some passion. We are the Orangemen and women of Scotland and we are passionate about our Queen and country."

However, many in the "Yes" campaign believe the spectacle of the controversial Orange Order marching through Edinburgh may give the pro-independence campaign another boost.

"The Orange Order represents the past," said chair of the James Connolly Society Jim Slaven. "The referendum offers us an opportunity to build a new Scotland without sectarianism." On Twitter Tom Doorley remarked: "Orangeorder marches in Edinburgh, thus helping to bolster support for a 'Yes' vote."

The presence of the overtly Protestant Orange Order marching through Edinburgh is a reminder of the country's sectarian past, though most people in both the "Yes" and "No" camps now believe the country has moved on.

With the vote on Scotland's future now just five days away, the campaign across Scotland is becoming increasingly fractious. First Minister Alex Salmond says the "Yes" campaign won't be bullied by warnings from banks and business about the future for an independent Scotland. A Guardian/ICM poll has the "No" vote on 51% and the "Yes" vote on 49% - with 17% still undecided.