Even though our faces now clashed with the £99 scarlet satin bra sprawled on the marble counter, we bravely continued to discuss the size required to fit his lady.
At Christmas, this is the kind of intimate conversation the assistants are used to in Janet Reger's Beauchamp Place lingerie shop in London. Alas, I wasn't. This was going to be a tough job.
There I was, an undercover reporter posing as a lingerie shop assistant. My mission: to gain insight into the male psyche at this time of year.
I intended to relay vital information such as what mistresses get for Christmas, the sexual penchant of the British male, and how they cope when it comes to buying strictly female frilly things.
But instead of learning about my fellow man, I was learning more about my own embarrassment level.
"Hang in there, you'll get used to it," whispered Minouch, senior assistant for 14 years.
At that point, the phone rang. So I left her to steer my customer in the direction of the matching thong and suspender belts while I took refuge on the blower.
"Hi, I bought a slinky black lace basque from you last year," said a deep, manly voice. I stood there speechless, finger poised to dial 1471. Then, remembering where I was, I croaked: "Er, was that for your lady, sir?"
"Of course," came the indignant reply. "What have you got that's similar this year?"
I glanced at the rails of frothy confections, then helplessly at Benedict, another assistant. As she held up various choices, I described them to the caller. "Ahh, we've a curvaceous silky black basque, trimmed with a solitary diamond stud."
"Sounds good. What else do you have?" said the man. Unsure, I offered to call him back, but curiously, the man was extremely reluctant to give me his home number.
Instead, he hung on until I continued: "How about a delicate ivory lace bustier, tipped with satin buttons and a scalloped edge? It's a limited edition, and quite adorable." I was starting to sound like a mail order ad for a plate of kittens.
"Umm ... describe the first basque to me again." This time, I lowered my voice a few octaves, then paused and huskily said: "Personally I'd be delighted if someone gave it to me for Christmas."
This did the trick. "I'll take it," he stated. "How much is it?"
Glancing at the price tag, I gulped. "Only £250, sir." "Fine. Send it to this address ..."
A sale! Not only had I made it as a bona fide shop assistant, but I'd also established a possible career in telephone sex.
"He obviously wanted a gift for his mistress," I later announced to Minouch, self-satisfied at my analysis. "Then you should have asked him where he'd like us to send the receipt - obviously, we can't send it to his home," sighed Minouch.
Taking pity on my naivety, the girls gave me another tip. "Men tend to buy white for their wife, black or red for the mistress. Usually, in two sizes smaller. And often at the same time."
Although I was now armed with vital information, the next customer, sadly, offered no chance to test the theory. A tweed-jacketed youth of about 18 had popped in to buy a sexy blue silk slip. It was probably for his nanny, I decided.
As he casually handed me a cheque for £185, I wondered at the kind of men who could afford to spoil their women so outrageously. "You can never tell who's going to be a good customer," advised Jackie, the manageress. "I insist everyone is treated equally." With that, timely bottles of champagne were offered to the horde of hovering customers, anaesthetising the pain of emptying wallets.
The telephone rang again. "Let me handle this," I volunteered confidently.
"Hi," breathed a woman's voice. "My lover is on his way to buy me a night-dress and negligee - can you make sure he chooses the best set you have."
"Sure, give me his description," I replied. "Umm ... basically, he's pretty nondescript," she answered. Poor guy. Forking out £2,000 only to be called "nondescript".
Twenty customers later, I found myself sporting a Chinese red silk negligee over my suit, for the appraisal of a dashing older man.
"Okay, add it to the rest of the stuff. The bra, the pants and suspender belt - all in the smallest size available." Time to test the theory. "Is it for a special lady friend, sir?" "No, my wife. The negligee is a separate present for our wedding anniversary."
Oh, how sweet. Hope springs eternal.Then, fondling the silk, he added dreamily: "It's our first year."