Rangers warned it could take them another 10 YEARS to compete with cash-rich Celtic for the Scottish title

That was the stark warning from one of the United Kingdom's leading football finance experts last night in the wake of the Scottish champions' interim results.

The Parkhead club announced on Monday that they had made a massive pre-tax profit of £18.6 million in the last six months of 2016.

That is a direct result of being involved in the lucrative group stages of the Champions League for the first time in three years.

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It emerged yesterday they are to receive a further €7.15 million, or £6.12 million, in June when the second half of their television money is paid.

Their financial situation is in sharp contrast to that of their Glasgow rivals Rangers who posted annual losses of £3.3 million last June.

The Ibrox club, whose directors are attempting to restore stability after years of corporate vandalism, have returned to the Ladbrokes Premiership after a four year absence this season.

However, Mark Warburton's side is currently in third place in the top flight table - a massive 27 points behind runaway leaders Celtic.

Dr Dan Plumley, a senior lecturer in sports business management at Sheffield Hallam University, has followed the off-field situation at Rangers closely in the last five years.

He praised the current board, who have charged Warburton with the task of finishing second and qualifying for the Europa League in the 2016/17 campaign, for setting realistic objectives.

But he believes it could take another decade before they can vie with Celtic, who are closing in on their sixth consecutive Premiership crown, for the league.

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"There is no quick fix for Rangers," said Dr Plumley. "Looking at the Celtic model, it does take time to get to that position.

"It is down to continually qualifying for the Europa League and for the Champions League and continually competing at the top of the league.

"There was never any doubt Rangers would get back to the Premiership one day. But once they got their it was always going to be difficult to close the gap with Celtic.

"There is, as they have found, a big leap from regaining Premiership status to competing for the title. It will take a fair few years yet."

Dr Plumley added: "Looking at the figures, with the financial gap at the minute and the potential prize money available, I would say they are looking at at least a five year period of transition and building.

"They can see where they are at that point in time. But it is very much a long-term project. In five years if Rangers have consistently qualified for the Europa League then they could anticipate that gap will begin to close.

"If it is being run in a sustainable way and their on field performances match up, I would speculate that they are looking at a five to 10 year plan.

"It is very much about building incrementally and making a financially sustainable business as well as a financially sustainable football team.

"Europa League qualification will allow them to gain some more revenue. If they reinvest that money in playing talent then they can close the performance gap with Celtic by signing better players on better wages.

"The best way for them to build is by trying to finish second, get into the Europa League and build their revenue streams from there. It does work, but it does take time."

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Celtic announced they have nearly doubled their revenue in the last six months of 2016 compared to the corresponding period in 2015 - a consequence of their participation in Europe's premier club competition.

Dr Plumley feels it will be difficult for Rangers to bridge the gap if the Parkhead club continue to feature in the Champions League group stages.

"The fact there is just one Champions League place, in the qualifying rounds, does create additional problems for Rangers," he said.

"They have to catch Celtic domestically in the first instance and then try and qualify for the Champions League."

Rangers supporters are refusing to buy replica strips and official club merchandise in protest at the unfavourable terms of the retail deal with Sports Direct which the current regime inherited.

Elsewhere, the Ibrox club isn't currently listed on a stock exchange having been delisted from the Alternative Investment Market when Dave King and his associates seized power back in 2015.

Dr Plumley feels those historical issues will prevent Rangers from bridging the gap on Celtic in the coming seasons.

"Merchandise is a vital income stream," he said. "If you are taking a third of their overall revenue stream away that will have a substantial affect on how much money they generate and then the future investment of that money.

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"That is one thing that is hindering Rangers when it comes to closing that financial gap with Celtic."

Dr Plumley added: "Listing the club on the stock exchange allows clubs to raise funds as well.

"But, to be honest, in modern day football, it isn't that important. It doesn't generate huge amounts of extra revenue.

"In English football a lot of clubs were doing it in the late 1980s and early 1990s. But all of those clubs have since delisted. I think you can still buy shares in Arsenal. But they are one of the only clubs.

"We have seen clubs move away from that stock market model of ownership. There are still opportunities to raise money that way.

"The Glazers have obviously listed Manchester United on the stock exchange in New York and Singapore to drum up initial investment.

"It isn't the be all and end all, but there is a possibility it could raise some funds. But a club nowadays very much wants to be in charge of its own revenue streams.

"Match day tickets and commercial deals are such big things these days with emerging markets and size of broadcasting deals."