ALLY McCoist last night demanded that the Ibrox club be 'cleansed' following the departure of Charles Green as chief executive – and revealed he fears his budget may now be slashed after his exit.

The Rangers manager stressed it is vital the club get the appointment of the new chief executive right, with current director of sports development and £1 million investor Craig Mather the favourite to land the post.

On a day when their 2-1 home defeat to Peterhead was completely overshadowed by events off the park, Rangers were also embroiled in a new row when they appointed the same financial firm that assisted Green's takeover of the club last summer as independent investigators into the conduct of the Yorkshireman and commercial director Imran Ahmad.

McCoist, though, wants this to be the start of a new chapter after two years of uncertainty. He said: "What the club actually needs is to be totally cleansed. We need to give ourselves an opportunity to move on.

"We need to cleanse ourselves so that everyone can see what has been going on and where this club is hopefully heading. We haven't had the chance to do that. In the last six weeks the whole thing has been all over the place with one thing or another. No matter who is in charge we need a bit of stability, there is no doubt about that. We definitely need stability.

"I would imagine my budget will have changed from what I was told it was initially. I was pleasantly surprised with my budget prior to the departure of Charles. I would settle for it not changing, but I have a sneaky feeling that it will.

"We're really far down the line with a lot of targets and a lot of players. I keep saying it's not an ideal situation because we can only sign players who are out of contract and we can only register them on September 1, so I think it's in our best interests to move as quickly as we possibly can and get them signed up."

McCoist said he had not expected Green's resignation on Friday, although he was also not completely surprised by it after a series of off-the-park dramas this season.

He explained: "I was a little bit taken aback when the news broke. I never felt we were beyond it all. I always felt there were things unfolding because there were stories appearing here and there. We were never going to get an opportunity to move on. You do wonder where the next hit is coming from, but we do need to move on."

The Rangers manager had been increasingly at odds with Green recently following his infamous comment about his side being the worst in Rangers' history, amid plots to axe the Ibrox management team of Ian Durrant and Kenny McDowall.

But he paid tribute to the outgoing chief executive, who wasn't at Ibrox yesterday. He said: "You have to give Charles credit initially at the start. We were in desperate need of someone coming in to buy the club and take us forward in terms of not even having a licence to play or any players. The biggest thing you can say about that is that he got us a licence to play and got a team on the park.

"Listen, Charles told everyone he was a straight-talking Yorskhireman and that's certainly what he was. Did everyone agree with what he said? Not at all. I'm not going to attempt to put the blame on one man for the club turning a bit, though, not at all. He said a lot of things that provided a lot of inches in the papers. I didn't agree with everything he said, but I agreed with a lot of what he said. I think that'll be the case with the next chief executive as well."

McCoist wants Rangers to take their time in appointing a new man in charge to ensure they make the correct appointment. He added: "It's more important to get it right. Whether it's appointing the chief exec or the commission, we must get it right."

Frontrunner Mather, 43 – who was at the Peterhead match – owns a sports management company and Nottingham packaging company and was brought into Rangers by Green.

Meanwhile, interim Dundee manager and former Rangers player John Brown – whose criticism of the Green following his takeover was one of the most memorable moments in a highly eventful year at Ibrox – said last night the news of the chairman's resignation did not come as a shock to him. Brown, who stood on the doorstep of the stadium last summer and asked to see the title of deeds of Ibrox and Murray Park, said last night that the current board of finance director Brian Stockbridge, chairman Malcolm Murray, and non-executives Ian Hart, Walter Smith, Bryan Smart and Philip Cartmell, would have to act swiftly if the club is not to end up in an even "deeper hole".

"[Green's exit] was going to happen anyway," Brown said. "It is going to be interesting. I am not surprised because I knew what was going on but I am trying to get a job at Dundee. Walter Smith and the other directors there I am sure will be on the case to find out what is going on, but it was always going to be the case because Charles Green wasn't the owner. If there is bad management, whether it is Rangers, Dunfermline, Dundee, Hearts or Celtic, I would say the same. The Rangers thing has to get sorted out sooner rather than later or it will be a deeper hole they will be in."

In a further twist, Rangers have risked further controversy with their choice of firm to investigate Green and Ahmad. Financial experts Deloitte – Green's own tax advisors, who helped advise him when he attempted to get a CVA after he took control of the club – will front the probe.

The club's supporters are puzzled why they have appointed a company with such close links to the Yorkshireman. Board member of the Rangers Supporters Trust Mark Dingwall said: "It would be far healthier if it wasn't Deloitte. They have a conflict of interest as both advisors in Charles Green's takeover and as his own personal tax advisors. It would be far healthier if the investigation was in the hands of a firm that were completely independent and had no previous involvement in the club."

The Ibrox outfit have also indicated that London legal firm Pinsent Masons are involved in the investigation.