The bayadere bears on her shoulder a vase of holy water, and the story of the ballet La bayadère is of her refusal to compromise. She could better her life in two political deals: become the high priest’s mistress, or later, when bitten by a poisonous snake, take the antidote and live on while watching her sworn lover marry the princess who he knows tried to murder her. She refuses both. She remains, morally, the vessel of a purity that it would kill her spirit to give up.

The Mariinsky Ballet has just completed a three-week season, with terrific highs (and the odd low). This was the 50th anniversary of the Mariinsky's (then Kirov's) first London visit, in 1961, and it is worth highlighting the role impresarios Victor and Lilian Hochhauser have played in the cultural life of London. They brought the Mariinsky to London in 1961, and, half a century later, they have once more given Londoners a summer of artistic richness, with 10 ballets, six choreographers and numerous casts. We owe a great deal to this extraordinary couple.

So, to work.

Great Mariinsky ballerinas are a breed apart, even from Bolshoi women. They take the stage with a consciousness of entitlement that’s thrilling to watch, and when this almost sacred sense of mystique and grace instilled in St Petersburg comes with vivid expressive distinction too, then there really is nothing like it. Even if three American 20th-century ballets might not be thought the likeliest territory to make such discoveries, what a night for ballerinas last night was. Viktoria Terëshkina and Alina Somova are on their way to joining the peerless Uliana Lopatkina at the high table.

It's 50 years since the mighty Kirov Ballet made their debut London tour - reeling from Nureyev's defection days before at the Paris airport. The tour was promoted by the unique impresarios of Soviet culture, Victor and Lilian Hochhauser. Half a century on, the pair are still indefatigably promoting the company, now named Mariinsky Ballet, whose season at Covent Garden opens on Monday, 25 July and runs to Saturday, 13 August.

White-knuckle crescendos loom large in that greater-than-ever conductor Neeme  Järvi's spruce Indian summer. Short-term bursts were the chief payoff in tackling Dvořák's deceptively simple-seeming Serenade for Strings with a huge department on all too little rehearsal time, but they also helped to pave the way for the two big events in Shostakovich's Seventh Symphony: not just the infamous "invasion" sequence based on Ravel's Boléro, but above all the final slow burn. It was ultimately here that Järvi's mastery of the long, inward line showed us what creative conducting is all about.

True to form the Mariinsky Ballet has already made programme changes for its Covent Garden visit next summer, not a fortnight after announcing its tour on 3 December. But we're used to it and it's all to the good. Substituting Don Quixote for the Lavrovsky Romeo and Juliet originally planned means a more traditional cast to the tour, a much more sure-fire box office, and a direct comparison between the St Petersburg virtuosos and their Moscow rivals at the Bolshoi who for the past two years have made Don Q their party piece.

Confirmation today of the astonishing news from Russia - Nacho Duato will indeed become the new director of the Mikhailovsky Ballet, St Petersburg’s second company, from the New Year. The Spanish contemporary choreographer will be the first foreigner to lead a Russian ballet company for more than a century.

Rape, marauding soldiers, peasants on the warpath and a flash hero - are we at the Bolshoi’s Spartacus once again? No, we’re at the Mikhailovsky Ballet down the road at the Coliseum where a rather more Erroll Flynn-type spectacle is being offered, Laurencia.

The Mikhailovsky Ballet is full of surprises. Predictably for a Russian company it brought a gala programme yesterday - unpredictably, it brought a rare example of St Petersburg 19th-century ballet comedy and a new commission of contemporary ballet. Neither of these is box office, so how refreshing is that? Then there were the thongs-and-glitter pas de deux of the strenuous 20th-century Soviet athletic style, and a classical jewel from Sleeping Beauty, and a wholly delightful court polonaise from a Glinka opera.

It would be tough for any Russian ballet company to come into worldly, balletwise London just ahead of the great Bolshoi, but the Mikhailovsky Ballet make a very pleasing impression in their first week at the Coliseum with a pretty and historically interesting Swan Lake and a gently antique Giselle, and dancing that more than most underscores the rare pleasures of period style.