Sinn Feins Michelle ONeill and Gerry Adams pass under a portrait of former DUP leader and first minister Ian Paisley at Stormont on Monday

In a development which will surprise many observers outside the DUP, Wallace Thompson also warned that unionist unity “won’t solve the problem we are now facing”, even though such a prospect attracts considerable support across the unionist spectrum.

Mr Thompson, a leading figure in the evangelical Christian Caleb Foundation and a former special adviser to Nigel Dodds when he was finance minister in 2008 and 2009, made the comments in a post on Facebook yesterday.

The former NIO civil servant said: “In a state of shock, many unionists are calling for one unionist party. Unionist unity is desirable but it won’t solve the problem we are now facing.

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Wallace Thompson said different times call for different responses

“The problem we are now facing is that the nationalist/republican people of Northern Ireland have placed their confidence overwhelmingly in Sinn Fein. We need to not only realise this but accept the implications of it.”

Mr Thompson went on to question the way in which the election had been fought by his party, with its relentless negative campaigning focusing on the possibility of Sinn Fein emerging as the largest unionist party with a bigger role for Gerry Adams. The DUP veteran said: “During the election campaign, I was surprised by some of the posts on Facebook from some DUP supporters portraying Sinn Fein as ‘Sinn Fein/Provos’ or ‘IRA/Sinn Fein’ and emphasising the IRA terror campaign.

“Now, I’ve been around a long time and remember those dark days all too well. I’m under no misapprehensions as to the nature of the IRA and its bloody campaign. We must never forget those days or those who suffered so much at the hands of republican terrorists.

“However, we now live in different times and different times call for a different response.

Wallace Thompson said different times call for different responses

“Let’s not forget that we have shared power with Sinn Fein for a decade (which made some of the Facebook comments I’ve referred to above seem slightly incongruous) and we have to attempt to move things forward.

“We have to do all we can to get the institutions up and running again. It will be hard, especially given Sinn Fein’s wish list, but I don’t know what other choice we have.

“Compromise is a dirty word in Ulster, but there is going to have to be compromise on all sides if we are to move forward.”

Mr Thompson added that “above all, we need to pray for our elected representatives as they seek to chart the way ahead”.

Mr Thompson’s comments are reflective of what some other other DUP figures have said more bluntly in private over recent days.

And on Sunday Edwin Poots spoke out publicly to warn that the DUP’s tactics in the election had contributed to the huge increase in Sinn Fein’s vote.

Mr Poots told the News Letter: “This was a wake up call for unionism.

“Unfortunately nationalists and republicans turned out in a way they haven’t done for a long time. We made a contribution to that.

“We have managed to get nationalists and republicans angry and that has led to them winning more seats as well and that’s something that we have to reflect on.”

However, other DUP figures have defended their campaign, which was relentelssly focused around Sinn Fein and Gerry Adams, with Arlene Foster mentioning Mr Adams 32 times during her speech at the party’s manifesto launch.

And some within the party believe that if Mrs Foster had not done so then the party would have performed even worse, potentially losing its top position, given the RHI scandal.

Yesterday South Down DUP MLA Jim Wells defended Mrs Foster.

Commenting on whether the DUP should adopt a softer stance towards nationalism and that such a straegy might not have enraged nationalist voters, he said: “I am certainly saying that Arlene Foster should stand firm against this pressure.

“We are still the largest party, we have still got the first minister and the first pick in the Executive.