Lord Bannside was taken to St Thomas’ Hospital, which sits directly opposite the Houses of Parliament across the River Thames, after feeling unwell on Wednesday afternoon.
Doctors carried out a series of tests before diagnosing a heart condition and he was taken into theatre for an operation to fit a pacemaker, which will regulate his heartbeat.
The 84-year-old was discharged from hospital on Friday and flew home to spend the weekend recovering in the care of his family.
But yesterday, the former First Minister was back at his desk in Westminster preparing for what could be a demanding week ahead with the Lords expected to sit through the night tonight as the deadlock over voting reform continues.
His wife, Baroness Paisley, last night paid tribute to the House of Commons medical team and doctors and staff at St Thomas’.
“He didn’t feel well in the afternoon at a meeting of cross-benchers in the Lords so we came down and got some help,” she told the Belfast Telegraph.
“It was totally unexpected because he had been well and addressed a big meeting in London the previous evening largely made up of ex-pats from Northern Ireland.
“The Parliamentary paramedical team and the staff at St Thomas’ Hospital were absolutely wonderful. They did a very quick job and we could not praise them highly enough. He is doing fine.”
Former Stormont junior minister Ian Paisley jnr, who replaced his father as MP for North Antrim, said: “He was discharged early on Friday and came home at the weekend but he is back at his desk today. He is feeling well and is doing fine.”
It is now almost six years since the couple’s other son, Rev Kyle Paisley, revealed his father had almost died from an undisclosed illness. He told his congregation at Lowestoft in Suffolk that Mr Paisley “... was at death's door and it was a very trying and testing time.
“I believe that he was saved because people prayed for him. He still has God's work to do and is looking 10 years younger.”