Two years ago, Tony Lomas was out enjoying a Chinese meal with his family in his favourite Essex restaurant when he took a call that was to change his life. One of the country's top insolvency experts, Lomas had just managed to polish off most of his dinner when he was asked to prepare for the possible collapse of Lehman Brothers.

Lomas, a PricewaterhouseCoopers (PwC) partner, was among a handful of City experts working frantically behind the scenes to prepare for an eventuality that they did not want to contemplate.

Lehman Brothers eventually collapsed two years ago today and the demise of the Wall Street bank sent shockwaves around the world, as stocks plunged and investors feared capitalism was on the brink. In the aftermath there were taxpayer bailouts of the banking system – notably Royal Bank of Scotland, HBOS and Lloyds TSB – as governments realised institutions could be "too big to fail".

On the second anniversary of the firm's collapse, Lomas is still a crucial member of the team – which has involved more than 10% of the 18,000-strong UK staff of PwC – trying to unwind the complicated affairs of a one-time titan of high finance.

In Britain alone, 800 people still toil each day on the administration of Lehman, which PwC partners hope they will never see the like of again as they fight to find the $17bn (£11bn) of assets claimed by clients such as hedge funds.

Lehman Brothers International (Europe) – as the firm is formally known – held $29.8bn of assets for clients when it collapsed. Within a year PwC had redistributed $13.1bn to the original owners but had managed just $1bn in the six months to the end of March as the size of claims became smaller.

Deadline

Unsecured claims are still coming in as the deadline to prove claims of 31 December this year approaches. The fees for administrators and lawyers are also mounting, estimated to be close to $900m. The costs in the US are even higher – they will top $1bn this month.

Mike Jervis, who along with Lomas is one of four PwC partners named as administrators, likens his role to a firefighter. "It's a bit like being a fireman. When the bell goes off you've got to go down the pole and get on with it," he says.

This was one pole, however, that none of the PwC experts had ever slid down before. Usually an insolvency expert might get a week or so to prepare for a company's collapse and then time to work with the management in the weeks afterwards to help pick through the operations.

This time, administrators had no time to prepare and were largely left to fend for themselves. "A lot of the decision-making was going on in the States, outside our care or controls. When you go into a big insolvency you usually have chance to get close to the company. That has added to some of the sense of incredulity about this case," said Jervis. "This is not typical."

While the administrators feel they are dealing with something that is truly unique, the markets that went into panic mode two years ago today appear to have forgotten what the fuss was all about. Both the FTSE 100 and the Dow Jones stock market indices are back to the levels they were at as the Lehman crisis began.

The price of gold, which yesterday hit new highs above $1,270 an ounce, tells a slightly different story as investors continue to seek safe havens during a time of uncertainty, this time caused by the fallout of the sovereign debt crisis and fears that developed economies may be sliding into a double-dip recession.

Some 300 PwC staff are now located in two floors at 25 Canada Square in Canary Wharf, near the former head office of Lehman, from which staff of the collapsed investment bank were pictured walking away with their cardboard boxes as the crisis shook the banking system.

A further 500 or so Lehman staff and contractors are also working on the administration, including Tom Bollard, formerly chief risk officer of Lehman's European operations. Their job is to sieve through all the "assets" they can find – be they shares in firms or art works, which will be auctioned on 29 September with an aim to raise £2m.

To help explain the complexity of the challenge they face in getting billions of pounds back to creditors, Jervis reveals that the team continues to find new Lehman ventures on a "regular basis". To date about 1,300 have been found and include special purpose vehicles of the kind that faced scrutiny as the credit crunch began in the late summer of 2007.

Interaction

"Not all the issues are easy to solve, such as the interaction between all the entities," Jervis said. Gross claims filed by the administrators to affiliate companies have reached $217bn so far.

The administration has not been plain sailing. A year ago a high court judge failed to give his approval to an asset recovery scheme that PwC had designed, saying he did not have jurisdiction, forcing the administrators to pursue their plan B, the so-called claim resolution agreement, under which the first returns to clients have been made.

Two years on, with the London headquarters in Bank Street empty after the Japanese bank Nomura, which bought much of the UK arm, moved into new City accommodation last month, Jervis warns that there are still lessons to be learned. He is a fan of "living wills" that would be drawn up by banks to help unravel their affairs when they collapse.

"We really have supported this idea for a living will." Jervis says. "It would have given us an incredible headstart with Lehman."