Carrow Road could return to the days of 35,000 crowds if Norwich City regain Premier League status, shareholders were told on Tuesday night.

Chief executive David McNally said the Canaries had to look at increasing ground capacity if they became re-established as a top-flight club.

But, speaking at the club’s annual meeting, he warned that adding 8,000 to the current capacity of 27,000 would cost �20m, money it would take years to recoup.

Not since the 1970s have City been able to accommodate 30,000-plus crowds. The final home match of the 1974-75 season, against Aston Villa, was watched by 35,999 fans, but three sides of the stadium were still terracing.

McNally said City’s current average home gate of 25,277 was “a distance ahead” of the Championship average of about 16,000, but he said the average Premier League crowd was about 35,000.

“We do have to consider looking at the opportunity to increase capacity when the time would be right,” he said.

Some Premier League clubs managed on much smaller gates, but survived thanks to big benefactors such as Dave Whelan at Wigan and Mohamed Al Fayed, who had put �200m into Fulham, he said.

“If there is no major investor we have to make the club self-sustainable and in the Premier League we would have to have 35,000,” said McNally.

But he pointed out that it cost about �2,500 per seat in a “new build”, so it would cost �20m to increase capacity by 8,000.

City would lose �1.4m in gate income from lost capacity while building work was in progress and it would take nine years to pay back the building cost, he said, adding that they would consider expanding the stadium only after two consecutive years in the Premier League.

“Only then would it be a viable proposition,” he said.

Club chairman Alan Bowkett said after the meeting that one side of the stadium was a prime candidate for redevelopment.

He said: “The obvious route is the Geoffrey Watling City Stand and whether you throw another layer on it, or you take it down and rebuild I don’t know.

“I think probably the sensible thing to do is bite the bullet, take it down and build a new stand but it means 18 months, possibly two years, without revenue. Then what do you do to the people in the Geoffrey Watling Stand, who tend to be the people who have been supporters for many generations? So it’s difficult.”

Bowkett said City were confident there would be an extra 8,000 fans keen to see Premier League football.

“We’ve done a lot of looking at the greater Norwich conurbation and the commuting population,” he said.

“About 500,000 people are in commuting distance of Norwich, compared to what, a 150,000 population. There isn’t another club for 50 miles.

There isn’t really another large scale sporting attraction like a rugby club or rugby league club, so we’ve got a captive market. We just have to make it accessible. The trade-off is between capacity and price.

“I’ve had some private conversations this evening with people saying ‘It’s getting a bit expensive, Alan’. And I know it is. There is only so far we can put the price up. And in the current environment when people are paying higher taxes, high inflation, flat salaries, one has to be realistic.

“But we’ve started our renewal programme for season tickets which, I’m absolutely amazed, has gone superbly well and we’ve got another six or seven hundred new subscribers for season tickets out of the blue.”