Mr Grau is blessed with a distinct resemblance to Ringo Starr, and his version of 'Boys' was every bit as good as the original, for which he deserves deportation. But one major advantage of the Manolos' short, sharp way with a song is that if you don't like a certain item, you don't have long to wait for the next, and we were soon into the classic 'El Muerto Vivo' (The Dead Man Lived) by the Sixties rumba king Peret.
It was the English language songs, a small but high-profile element of their repertoire, which the Manolos seemed least sure about when I visited them in a Barcelona theatre rehearsing for their British debut last week. 'Do you think the English will understand?' asked various Manolos, with a mixture of amusement and concern, showing me the phonetic lyric sheet they'd prepared for their version of the Eric Clapton song 'Lay Down Sally' - 'AIF BIN TRAYING OL NAIT LONG JAST TU TOC TU YU . . . ' In the event, they needn't have worried. Judging by the enthusiastic front-row chants, their moderately sized first night London audience at the Equinox, Leicester Square on Sunday was almost wholly Spanish.
To the Spanish, the Monolos are big stars and the major component of what for the last couple of years has been hailed as the new Barcelona rumba boom. Although an assortment of experiments in flamenco-rock from Madrid and Seville had accompanied the gradual rehabilitation of Andalucian culture from its retrograde, Francoist associations, the quite distinct gypsy rumba style of Catalonia remained lowbrow kitsch to the general public, a music consigned to cheap cassettes sold in highway truck stops.
Now kitsch rules, and the Sixties and Seventies are all the rage. The outside world glimpsed the very large tip of the iceberg last summer when the closing ceremony of the Olympics featured a 20-minute concert of rumba, chosen as the most representative indigenous popular style of Catalonia. Of the three acts, two were authentic gypsy rumberos. The third, the Manolos, in their brightly coloured flares and wide collared polka-dot shirts, were not. The Manolos are as tongue-in-cheek as their name (Manolo is a proletarian-sounding diminutive of Manuel); they are only peripherally rumberos, and yet it is they who are the chief beneficiaries so far of the new rumba boom, with two major hit albums and 24 months of sell-out concerts behind them.
The Manolos' great breakthrough, two years after their formation from a pair of Barcelona rock groups, came via their espousal of the works of Lennon and McCartney. In this, curiously, they are reviving another Catalan tradition. Sophisticated Barcelona came nearest to participation in the Swinging Sixties, and a quartet from the city, Los Mustang, purveyed Beatles songs in the form of hugely popular Spanish language versions put out by EMI to introduce the Fab Four gradually to the Spanish market. Thirty years later, the Manolos' version of 'All My Loving', adorned with Lai-lo-lai-lo-lais and elongated vowels, launched the Manolos as national stars.
The best songs in the Manolos' act, however, are their least parodic, above all those by the King of Rumba, Peret. The 'return of Peret' is the second major plank of the rumba boom. Sitting in his study last week - flashy repro furniture, wall-mounted gold discs, grandchildren wandering in and out - the maestro showed me his first record, 'Lola', an EP dating from 1957 with cardboard fold-out flamenco dancers that pop up when you open the sleeve. 'I used to sell these to tourists in the summer on the Costa Brava. Then my next record, 'La Noche Del Hawaiyano', was a big hit and I became a star.'
Peret was born 57 years ago into a comfortably-off gypsy trading family in the barrio of Sant Antoni, a block away from the community's epicentre in the Calle de la Cera. 'My models were Elvis Presley, Perez Prado, and Celia Cruz,' says Peret, lighting yet another cigarette, 'the flamenco feeling I was born with.' The best records from the first rumba boom - those of El Pescailla, Peret, and Los Amaya - are absolute jewels, and their distinctive elements are the fast palmas (hand clapping) and the guitar style nowadays referred to as ventilador (fan) because of the rotating strum of the right hand.
Peret himself is a ventilador specialist, as he demonstrates, reeling off a series of different combinations of strumming and slapping his guitar's body. 'It's actually very rare to find guitarists who can do this properly,' he remarks. The technique was first named by Gato Perez, an Argentinian rumbero in late Seventies Barcelona, whose zeal and talent helped save rumba from total obscurity through its unfashionable years. Peret was absent from the scene at this time, having been reborn as a preacher in the Sant Antoni congregation of the Evangelical Church of Philadelphia.
When he re-entered the musical fray in 1991, due to a combination of disenchantment with organised religion and the pleas of Barcelona taxi drivers, the religious rumbas he had been confined to composing stood him in good stead. One of them, reworked as 'Gitana Hechicera' (Gypsy Enchantress), a classically catchy Peret tribute to the charms of Barcelona, became a huge hit for Peret himself, the closing anthem of the Olympics, and now, the spearhead song in Los Manolos' attempt to conquer the international market.