He tasted 16 different chocolate bars, and found the cheaper brands fared surprisingly well against luxury alternatives.
Out of eight dark chocolate bars tried by Mr Ronay, the cheapest of them all, Marks & Spencer's Swiss Extra Fine, at 59p per 100g, easily came out top. The bar's "excitingly powerful" character nudged into second place the "good but absurdly expensive" (pounds 3.10 per 100g) offering from Fortnum & Mason, the superior food emporium in Piccadilly, central London.
Out of eight milk chocolate bars sampled separately, the pounds 3.10 Fortnum & Mason bar was judged equal second with Galaxy - a relative snip at 62p per 100g.
Both were beaten, however, by Lindt Swiss Milk, which was praised for its "impressive balance between sugar and chocolate".
Bottom of the dark chocolate test was the German-made Ritter Sport, dismissed as "crude", while the United States-made Hershey bar came last in the milk chocolate league."You need to be Sherlock Holmes to discover a chocolate taste in this," Mr Ronay said.
Of other popular high street brands tasted, Cadbury's Dairy Milk came fifth in the milk section and Bourneville seventh among the dark chocolates.
Nestle's milk chocolate Yorkie bar finished only ahead of the Hershey bar, with Mr Ronay describing it as "sickly sweet and a crude taste".
Overall, he said that he was surprised at the wide differences between the various chocolates. "There are more differences between the chocolate bars than meet the eye. The lesson is that it's well worth making sure you choose a good chocolate."
A spokeswoman for Fortnum & Mason said: "Our chocolate bars are handmade by a small, independent chocolatier using fine-quality ingredients.
"As they are not mass produced we do not enjoy the economies of scale in production of large companies, but we do ensure its taste is maintained by a high percentage of cocoa solids."
Paul Kirkwood, a spokesman for Nestle Rowntree, defended the company's product, saying: "The results of the survey are not reflected by Yorkie's recent market performance.
"Since last year's relaunch, sales of single Yorkie bars have increased by 15 per cent to pounds 36m, demonstrating Yorkie's continued and widespread popularity."
Gavin Tarrant, of Lindt UK, said: "I am not surprised that our milk chocolate came out top, but I am surprised that the plain chocolate did not win."
A spokeswoman for Mars, manufacturers of Galaxy, said: "We are delighted with the results. Galaxy is a very smooth, creamy chocolate which consumers like."