Time was when being a gentleman was a straightforward affair. Right school, right regiment and don’t forget never to wear brown in town; pretty much everything else flowed from that.

Such old-fashioned values, however, do not hold in the first decade of the 21st century, not when the leader of the Conservative Party deems it acceptable to be seen in public without a necktie. A chap wondering how to behave could be forgiven for feeling a little confused.

Help is at hand, though, with the publication this week of Debrett’s Guide for the Modern Gentleman, a volume that describes itself as “an essential handbook for those who wish to rediscover the art of gentlemanly behaviour for our age”. Armed with 192 pages of advice, from how to buy a racehorse to how to seduce a woman, I tried to see how much I could master in just one day.

It was a tough call, as there was a lot to get through. A modern gentleman should have read the right books (Herman Hesse’s Steppenwolf? Do I have to?), have the right DVDs and own a top-notch sound system. He must also be able to do everything round the house from sanding a wooden floor to changing a plug. I wondered if I had time to hire a floor-sander before work, and changed a plug instead.

A modern gentleman should be well groomed. It was not until I consulted the guide that I realised I was little better than a rank amateur when it came to shaving. The instructions contained no fewer than 11 steps to the perfect shave, including the use of a hot flannel, shaving cream, another hot flannel, more shaving cream, a cold flannel, moisturiser, shaving balm and aftershave gel. And a razor.

I decide to have a proper shave at Trumper, the traditional barber. It was one of the great grooming experiences of my life, made all the better by the offer from the barber of a glass of malt whisky afterwards. Before that, though, there was the question of how to get to Trumper’s. Surprisingly, the guide permits the use of public transport, something a traditional gentleman would never contemplate.

Then, as advised by the guide, I was off to Savile Row. Having a bespoke suite made at Richard Anderson, I learnt, involves 25 separate measurements and can take up to five fittings. I also learnt that I have got wide hips, a flat seat and a slight drop on the right. That is the mark of a gentleman – taking that sort of talk from his tailor without complaint. I also learnt that a two-piece suit in English worsted would set me back about £3,400.

On to lunch, the greatest test of all. At Bentley’s Oyster Bar & Grill I meet a friend, Beatrice Ballard, the television producer, and pass the first hurdles. The social kiss: right cheek first, skin makes “brief, light contact”; compliments on your companion’s appearance: get them in early.

The guide states that I cannot tuck my napkin into my collar, which is a blow considering that I have ordered linguine with clams. How am I to keep my tie (knotted with the recommended half Windsor) and shirt free of the inevitable collateral damage?

It is a nerve-racking experience trying to eat my linguine without splashback. Afterwards, though, my tie appears to be unblemished. Could I have passed the ultimate test?

Alas. When I get home, I notice a small spot of grease on my shirt. It is almost undoubtedly clam sauce. Valentine Low, Modern Gentleman (Failed).