By Nick Assinder Political Correspondent, BBC News website

Civil servants. A bunch of bowler-hatted, pinstripe wearing Sir Humphreys or untrustworthy, politicised servants of the Downing Street spin machine?

Hard hat rather than bowler for Sir Gus

Neither image is particularly flattering - or accurate. Yet both caricatures reflected something of the nature of that great British institution, the Whitehall mandarin.

And they are images new cabinet secretary Sir Gus O'Donnell believes are either outdated, unjust or simply wrong, and that he is out to correct.

So, on the first day in his new post he hit the road, determined to destroy the old stereotypes. The BBC News website hitched a ride with him.

This is one way to get close to the most powerful man in Whitehall, squeezed - literally cheek to cheek - alongside him and his press minder in the back of his Rover.

Sir Gus, who still can't quite get used to the Sir bit, has lost none of the easy, friendly manner that made him such a popular press secretary to prime minister John Major between 1992 and 1994.

He is candid about that period, saying it was a good job "to have done", but he moved on at the right time.

Every one a civil servant

As for today's diary of engagements, Gus is on a mission.

"I want to show that all civil servants don't just sit behind desks in Whitehall. Neither the "Yes, Minister" view or the new idea that special advisers are in control are right," he says.

Sir Gus litters his remarks with words like "dynamic, professional, flexible, productive and adaptable" and points out a career in the civil service is second favourite amongst graduates.

He accepts there have been difficult times for the service in the wake of claims Whitehall was politicised by New Labour, and Alastair Campbell in particular, with special advisers given too much power.

"The problem with special advisers is when you get bad ones. The problems arise when ministers are looking for political advice and don't get it from advisers so start looking to the civil service to fill the vacuum.

"The more professional we are, the less ministers will do that".

We arrive at a derelict site currently being cleaned and prepared for a major development of homes, business, a hotel, school and so on.

Right by the river and with the cathedral and castle remains providing a backdrop to the development. "Desirable location" leaps to mind.

This is all hard hats, Wellington boots, eye shields and fluorescent jackets.

And just about every one of the couple of dozen individuals on the site are civil servants.

This is what the visit is all about then.

We are told the private sector simply wouldn't take on the project and it was only a public-private partnership that made it happen. And it's civil servants leading.

Gus and a group of hard hats disappear in a four wheel drive and a cloud of dust for a tour of the site.

A successful test drive

At my count, some half dozen government departments or agencies are involved, from John Prescott's office to the ministry of agriculture and food.

OK the digger driver - looking slightly bemused at the requests to pose his machine for the camera - is not a civil servant. Still he seemed delighted to meet the cabinet secretary - all in a day's work.

What would a normal day for the cabinet secretary be like? Clearly not racing around the south east without a minister or special adviser in sight.

First off, Gus has a family life - a wife and 14 year old daughter - and he values it.

So it's breakfast with the family before getting to the office by 0800 after a 25 minute driver from home. Sometimes straight to the gym, other days into meetings.

First meeting will often be with the prime minister, sometimes the cabinet. And every Wednesday there's an hourly meeting with Whitehall permanent secretaries.

He will aim to get out of the office and back home for dinner with the family.

Gus isn't into the competitive game of first in, last out of the office (gets my vote). But he is also realistic. Things will "slip".

Press aide has already phoned ahead to say we will be a little late.

Straight into the only open press event of the day - a picture opportunity with Gus handshaking his way through the building.

For the umpteenth time today I am reminded by officials that the passport service has won prestige customer service awards two years running.

It is probably worth boasting about bearing in mind the chaos that once characterised this service.

I am slightly taken aback, however, by the announcement to those waiting to get their passports: "Ticket one thousand eight hundred and ninety four - please go to window seven".

It's not how it sounds. There are probably twenty people at most sitting around in the quiet, airy waiting area. It's the cheese counter scenario - the ticket roll hasn't been replaced for some time.

There are no ugly scenes from people about to lose out on the holiday of a lifetime because they can't get their passport back.

Simple measures like introducing the latest technology and even moving offices closer together to create a sort of passport production line seem, to have done the trick.

And, by the way, did I mention this service - and the civil servants running it - have won two prestigious customer service awards in the past two years....

A handful of hacks have come along to chat to the new cabinet secretary on his first day and hear the message about the civil service.

But the questions are dominated by the issue of trust - raised earlier in the week by Sir Alistair Graham, the public service watchdog.

It is not what Gus wants to concentrate on, but that is the nature of the beast.

He repeats the message about special advisers having to be good at their job and accepting there is work to do to rebuild trust with the public.

We see the, currently non-functioning, biometrics "pod" which will take your passport photo, scan your iris, take your fingerprints, and make you a dry martini while it turns it all into a bar code for your new passport.

Now with the customer service officers. Surprising fact: security officers had to relieve customers of some 200 knives over the past year. Plus, in one case, a handgun which the customer handed over, then came back to reclaim once his business was done.

Gus has a business meeting with the prime minister. I am not invited.

Nearly an hour after setting off and we should be there by now, but thanks to road works and a diversion somewhere around Finchley traffic is at a standstill. My suggestion that the cabinet secretary should call in a blue light escort is met with a wry smile.

Driving examiners reveal we have arrived just as the latest batch of test-takers are due back.

Gus wants to meet a passed candidate and I detect nerves.

"How many went out?" he asks. "Seven".

"And what is your pass rate?".

"Forty per cent".

Top score on driving test

"So 2.8 of the pupils should have passed," Gus declares.

So that's why he was such a success at the Treasury.

But horror of horrors, all but one of the examiners is back and all have failed their pupils (is that weeping I can hear outside).

Still, let's have a look at the fabulous new high tech kit which will allow you to do just about everything test-related online.

Time is running out - Gus has to head for Heathrow for a flight to Scotland for more hands-on meetings.

Enter 28-year-old Vincent Hewett, a first time pass. And, second relief, he appears delighted to see Gus.

Fears about the cabinet secretary being seen alongside a Learner plate (hardly appropriate in his case anyway) are cast aside.

This is the way to end the day and just to round it off, Gus scores four out of five on a computer simulation on hazard perception.