Prime Minister Manmohan Singh on Thursday said that the office of Lok Sabha Speaker has been "truly elevated and dignified" by Somnath Chatterjee, who set himself as a "role model".

"We strained your patience and at times, even your conscience. There were unusual times in which you had to take a call between defending parliamentary propriety and heeding to the demands of the organisation that you had spent a lifetime building," he said.

In a message read out by External Affairs Minister Pranab Mukherjee, the prime minister said: "In transacting the business of the parliament you have become the role model." The Prime Minister's brief statement was read out by Leader of the Lok Sabha Pranab Mukherjee on the last day of the last session of 14th Lok Sabha, which adjourned sine die.

Noting that on such occasions "your sagacity prevailed", he said he had no words to express the gratitude of the House for upholding the dignity of both the high office and the institution "in times of personal trial".

"History would be the best judge of your unique contribution. You stood like a rock to defend our best Parliamentary traditions and in doing so have raised the bar for those to follow," he said.

Earlier, the Lok Sabha speaker described his five-year tenure as Lok Sabha Speaker as a "great opportunity".

"It was a great opportunity. I never expected it but I got it," Chatterjee told reporters in the Parliament premises Thursday, on his innings as Speaker.

Refusing to comment on the lows, he said "I don't want to say now. After I actually quit, I will say."

Chatterjee served as Speaker in one of the most eventful Lok Sabhas which saw many controversial debates.

On the worst moment of the 14th Lok Sabha, Chatterjee said, "July 22, 2008 when those notes were shown." He was referring to the cash-for-vote case, when three BJP MPs displayed wads of cash in the Lower House and accused the UPA government of offering bribes to MPs to win the Trust Vote.

Chatterjee, who often expressed his anguish over the misbehaviour of MPs in the House and at times even threatened to resign, said he did not find anything amiss in being called a "headmaster".

"What is wrong with a headmaster...It is a good profession. Don't we respect headmasters, what is wrong, how is it derogative?" he said.

The former CPI-M leader had also earned a reputation of upholding the high standards of the legislature. He hoped his successors would bring more laurels than he did.

"Obviously. I hope more than me," he said.

Chatterjee, an MP from Bolpur in West Bengal, has announced that he would not contest elections and was bowing out of political life.