Karel Čapek, the great Czech writer who pioneered some of the most prophetic dramatic fantasies of the early 20th century, thought Janáček was nuts to want to set his wordy play about a 337-year-old woman to music. He could not have anticipated what that septuagenarian genius would achieve. Some of us felt similarly doubtful about singers performing this most conversational of operas with scores and music stands in a "concert staging".

It's not so long since Daniel Barenboim sat around a table with Israeli officials telling him that Wagner couldn't be played in the homeland when someone's mobile fanfared the "Ride of the Valkyries", demolishing the opposition's case. At the opposite end of the scale to all that flash of battle-lust came last night's unexpected first encore to a Wagner second half – the Act Three Prelude to Die Meistersinger von Nürnberg.

The mid-way point of the BBC Proms has just passed. Attention during the eight-week season will inevitably tend to gravitate towards the novelties, “events” and one-offs, but one pre-condition for the summer to be going well is that the Proms' backbone ensemble, the BBC Symphony Orchestra, which plays no fewer than 12 of the concerts, has to be on good form. Ideally, they should be playing well across a wide range of repertoire, they should be getting full or nearly full houses, and their relationship with their principal conductor should be positive and productive.

Jamie Cullum has been perceived as the Tim Henman of Jazz. Talented, technically great, a successful career, excellent voice and top-notch pianist, and a nice guy you could take to tea with your mum, but not really challenging or world-beating. Yet there were interesting flashes of greatness in last night’s concert.

Conductor, arranger and composer Jules Buckley is a notable champion of non-classical orchestral music. He has pioneered orchestral arrangements with singer-songwriters such as Laura Mvula, Anna Calvi and Caro Emerald. Even more boldly, he has established orchestral collaborations with numerous artists from rock and electronic music, including the Arctic Monkeys, Professor Green, Basement Jaxx, and electronic improviser Beardyman.

Superior light music with a sting, done at the highest level: what could be better for a summer lunchtime in the light and airy Cadogan Hall? Our curator was that most collegial of top soloists, trumpeter Håkan Hardenberger. He'd invited colleagues of many nations, all of them first rate, but it was almost a given that chansonnier-composer HK Gruber would steal the show.

If the BBC were to plan a Proms season exclusively devoted to youth orchestras and ensembles, many of us would be delighted. Standards are now at professional level right across the board. 20 years ago, the National Youth Orchestra of Scotland (★★★★★) couldn't compare with its Great British counterpart; now, although the age ranges are slightly different and the (or should that be the) National Youth Orchestra (★★★★) has vast wind and brass sections, playing levels appeared equal.

"Let the song speak, I pray," exhorts the Bard in the Prologue to Duke Bluebeard’s Castle, "Listen in silence." This was a night for leaning in and listening closely, despite the large forces arrayed on stage for Dvořák’s Cello Concerto and Bartók’s opera.

The Aurora Orchestra’s gimmick at Prom 21 was the same as in the last two seasons: playing a major classical symphony from memory. This was touted as an “astonishing feat” by the concert’s on-stage presenter Tom Service but, although unusual, is it really that extraordinary? When I go to the opera I am not moved to congratulate the singers on performing without music. In fact, the lingering on what should be an incidental feature was in danger of obscuring a more interesting point: the excellence of the orchestra’s actual playing.

Like Prokofiev in his full-length ballet a century later, Berlioz seems to have been inspired by Shakespeare's Romeo and Juliet to bring forth his most compendious score. John Eliot Gardiner, who knows and loves every bar of light and shade in this great Berlioz kaleidoscope, offered even more of it than usual at last night's Prom.