'We insist our ladies swallow everything,' says Terry Hasdell. And indeed they do - everything from McVitie's Jaffa Cakes through KP Frisps to Terry's Chocolate Oranges and Ross Young's Linda McCartney vegetarian golden nuggets. Mr Hasdell's 18 'ladies' are product assessors, 'taste-testers' to you and me, based at the research and development unit of the United Biscuits group in High Wycombe, Buckinghamshire.

Anyone who wants to join their ranks, as I am hoping to, has to pass three tests set by Mr Hasdell, the unit's sensory research manager. One is to prove that the candidate can distinguish between sweet, sour, salty and bitter; the second is odour recognition; the third - biscuit sampling. I am joined for the test by Rebecca Shepherd, a United Biscuits communications executive.

Test one, and I reckon this is going to be a pushover. My task is to detect weak traces of sucrose (sweet), sodium chloride (salty), citric acid (sour) or caffeine (bitter) in 10 cups of water. Although it is difficult at first to distinguish anything other than the usual traces of chemicals you find in tap water, a little retuning of the palate enables me to identify nine cups correctly.

The odour-recognition test is a different matter. This time the brief is to sniff the contents of 20 vials and name the smells as precisely as possible, or say what I associate them with.

Mr Hasdell advises us to sniff gently. 'That's the way to get the smell into your olfactory bulb,' he says, stabbing a diagram of the head with his finger. 'If you want to see how not to do it, watch an amateur wine taster snorting wine; it will go straight past the olfactory bulb and into the lungs.'

The first two vials are easy: peppermint and liquorice (in fact I prove to be slightly wrong with the latter - it turns out to have been aniseed) but I am soon made to realise how much less attention we pay to our noses than to our palates. Many of the smells presented to me are highly evocative, but I am hard pressed to recall where I know them from, let alone put a name to them.

Number three, for instance, is achingly familiar but I cannot even attempt an answer. Rebecca has a stab at cinnamon but is hopelessly wrong. In fact it is amyl acetate, the dominant smell in nail-varnish remover and pear drops.

I get full marks for identifying one aroma as 'lemonish - some kind of boiled sweet from childhood' but Rebecca also gets full marks for 'lemon Opal Fruit'. It is geraniol, an aromatic alcohol used in perfumery - and, indeed, in Opal Fruits.

Some of my reactions reveal rather more about me than I would like. Number 18, for instance, furnishes irrefutable proof that I have not yet achieved New Man status. I describe it as 'women's toiletries'. It turns out to be a lemon aroma used in washing-up liquid. Mr Hasdell awards me two out of five as a gesture of male solidarity.

Even more worrying is what I detect in vial 13 - absolutely nothing. Yet vial 13 is one of three labelled with a red sticker to denote extreme potency. My fears prove to be well-founded when Mr Hasdell reveals it to be a strong rancid smell. Official confirmation that I no longer notice the growing pile of unwashed socks in my bedroom.

We tot up our scores. I have earned 60 out of 100 which, Mr Hasdell says, just scrapes a pass, although he would have preferred 65. Rebecca has scored 54, and after getting only three right in the water test, she is unlikely to be switching departments. Previous candidates have scored as low as 30 and as high as 85.

For the final test Dr Zoe Baines, a senior sensory research analyst, puts two McVitie's Rich Tea biscuits in front of me. 'I want you to sample both these biscuits and tell me what differences you notice,' she says.

Gingerly I nibble biscuit A. Then I try a morsel of biscuit B. A little sweeter perhaps? A little more crunchy? It might well be, but my palate refuses to register any distinctions.

Now I take an almighty chunk out of biscuit A, hoping that my taste buds will be overwhelmed by the volume. Then a similar mouthful of biscuit B . . . but they still taste exactly the same.

Finally I confess. 'I can't tell any difference at all. That's not a very good answer, is it?' 'No, that's not very good,' says Dr Baines.

We rejoin Mr Hasdell for a final decision over whether to take me on. 'He couldn't tell the Rich Teas apart,' says Dr Baines.

'Yes, but did he say which of the two he preferred?' asks Mr Hasdell. Dr Baines admits that I did not. 'Well, that's all right then,' decides Mr Hasdell. 'You have passed the test. The vital thing was that you didn't get side-tracked into subjectivity.'

Unlike consumer-research panels, the assessors' job is not to express preferences for the products they sample. 'If you ever use the word 'like', I'll make you go and stand in the corner,' Mr Hasdell warned me during my preliminary interview.

But before I can sign up for life, my fatal flaw is exposed. I reveal that I suffer from hay fever. 'In that case I will have to turn you down,' says Mr Hasdell. 'If there are times of the year when your acuity is impaired, I am going to have to say no.'

I need not be ashamed of my failure. When Mr Hasdell first advertised for assessors in a local paper 10 years ago, he received 138 applications. He tested 40 and only 15 were up to standard.

To show that there are no hard feelings, he lets me sit in with that day's assessment panel. Donning a white coat, I am ushered into a room where I sit at a large table with eight of the 'ladies'.

Aged from 25 to 60, they each work for one hour three mornings a week. For those who like their socio-economics based on what newspaper people favour, this lot are Express or Mail readers. Some of the current team were among the original recruits. They are not going to get rich from this job, but they enjoy having an outlet for their heightened sensory perceptions.

Their skill is undeniable. Two trays of digestives are brought in and we put a couple of each on our plates. At a given signal, they all pick up a biscuit, break it in half and sniff it. Then they start to nibble, then munch, scribbling notes as they masticate. The process is repeated with biscuit B.

Each of us has to fill in a form, which asks us to rate samples A and B for such qualities as odour, crispness, crunchiness and how smooth a paste they make in the mouth after four chews.

I find that I am devoting the best part of my energies to suppressing a fit of giggles. It is most unnerving to watch and listen to eight women in lab coats crunching their way through digestive biscuits with the diligence that others devote to assessing a Chateau Lafite '61.

Once I have adjusted to this surreal situation, I settle down to comparing digestives A and B. The trouble is that I cannot even distinguish the categories for assessment. What the difference is between 'crunchiness', 'crispness' and 'hardness of bite' I shall never know.

As soon as everyone has finished, Dr Baines asks which biscuit we had found harder in texture. All of us, except for Liz, think it was B. Which broke down quickest into a paste? This time we all plump for A, apart from Jenny.

The fact that we are virtually unanimous tells the research unit a great deal. Dr Baines now reveals that biscuit B was the traditional McVitie's Digestive, consumed at the rate of five million a day. Sample A was the new McVitie's Digestive Light, containing 25 per cent less fat. If the assessors are consistent in noticing a difference between the traditional and the light varieties, it means that some fine-tuning is still required to give the new product that essential 'digestiveness' which the British public knows and


The second dish of the day is Roysters, a KP potato snack that was launched last year. The aerated surface of a Royster is to the potato crisp what Aero is to Cadbury's Dairy Milk. Accordingly, the panel must decide which of the two samples has more bubbles and which has bigger bubbles.

This time, when we go through our analysis at the end, we are split. The divided opinion actually pleases Dr Baines and Mr Hasdell. Samples A and B are made with potato flakes from different suppliers. If we cannot tell them apart, it means that both suppliers are providing to specification.

Mr Hasdell and Dr Baines insist that the fact that all the tasters are white, female and from similar backgrounds does not make them unrepresentative. Wherever you go, they claim, everyone distinguishes between bitter, sour, sweet and salty in roughly the same way.

'When I did my PhD, I found that students from all round the world could appreciate different levels of sweetness,' says Dr Baines. Her doctoral thesis was 'The influence of food texture on flavour and taste perception'.

What this homogeneity of taste perception means is that theoretically any of us can become one of Mr Hasdell's assessors. But don't go besieging his office. Most recruits these days are recommended by members of the existing team. Still, if a woman ever approaches you at a coffee morning in High Wycombe and suggests discreetly over a Hob-Nob that you join the taste-testing team, jump at the chance.

(Photographs omitted)