On a hot, humid summer’s evening, Sakari Oramo made his debut as Chief Conductor of the BBC Symphony Orchestra. That the occasion was the first night of the BBC Proms 2013 didn’t seem to bother him. The Finn’s combination of serenity and confidence – and just enough passion to assure us that he was enjoying it – set the tone for an intriguing, if oddly assembled programme. Tonight felt like two concerts rolled into one. Rachmaninov and Lutosławski’s diabolically inventive Paganini variations filled a substantial slot before the interval. They were flanked by works by three British composers in a more contemplative, awe-inspiring mood. By the final ebb and flow of Vaughan Williams’ hour-long Sea Symphony, the first half felt a world away.

The first half could have stood alone. The world première of Harmony by Julian Anderson was a beautiful opener. It was artfully shaped and fully conveyed the wonder in a poem by Richard Jefferies, taking Time as its muse. The BBC Symphony Chorus’ sopranos captured the attention straight away with a lovely exposed melody, while the orchestra went on to provide bursts of energy and some ear-catching percussion. This piece is stuffed with colours, which were vividly brought to life. But I would love to hear the elements in it expanded upon. Its text may imply that time stands still during music, but it’s a shame Harmony only lasted a few minutes by the clock. Starting the Proms with new music, by a living composer, feels right. Yet giving them such a small slot is surely not enough.

The inevitable representation of centenary composer Benjamin Britten smoothly succeeded Anderson. The BBC SO were in their element in the Four Sea Interludes from Britten’s opera Peter Grimes – an approachable choice that encapsulates the composer’s ability to draw images with sound. An evocative, tense “Dawn” was followed by the familiar dancing, syncopated steps of “Sunday Morning” with its ill-fated optimism. This began a little heavily, but quickly found the playful tone representing Grimes’ young apprentice. Haunting percussion provided warnings of a darker mood to come. When it did arrive, the “Storm” that followed “Moonlight” was brilliantly executed.

There was a break before the Rachmaninov Rhapsody on a Theme of Paganini – fortunate, otherwise the Romanticism would have been a blunt change of styles – to move the piano. When Stephen Hough stepped up to play it, he looked relaxed; after all, he is no stranger to the stage of the Royal Albert Hall. His relaxed air was carried into his performance. The moods in these Paganini variations change abruptly from one extreme to another and the technical demands on the pianist are considerable. Hough clearly enjoyed the moments of demonic flair as much as the more romantic passages. In fact, he seemed to be pushing the tempo rather more than the orchestra, and I felt that certain minutiae in the piano part were swept over in the process. But the accomplishment in his performance was still impressive, and there was plenty of personality in his interpretation. The rubato lilt in the inverted eighteenth variation was particularly sumptuous.

Both in the delicate moments and the spikier phases where the main theme reasserted itself, Oramo displayed clear chemistry with the BBC SO. He blended into the orchestra, an understated presence but very much a commanding one.

It was a risk to place Witold Lutosławski’s variations straight after the Rachmaninov. This didn’t quite pay off; it was a heavy dose of the same Paganini theme. But it created an interesting juxtaposition of styles. Composed as a piano duet during the Second World War in Nazi-occupied Poland, then re-scored for piano and orchestra in 1978, Lutosławski’s Paganini Variations are a freer, wittier and more surprising set. The sense of progression found in Rachmaninov’s Rhapsody isn’t there, but brash inventiveness, rhythmic games and the odd flicker of tonal instability make it an exciting piece to hear. Hough again seemed to enjoy this as much as the audience, and displayed the calm mastery which has become his hallmark.

Ralph Vaughan Williams’ A Sea Symphony took up the entire second half. It’s his only choral symphony and one that took a great deal of effort to complete in 1903–09. The only link with the first half tonight was the shared sea theme with the Britten. Baritone Roderick Williams and soprano Sally Matthews were soloists in this giant hymn to the seas, in which the orchestra frequently come second to the voices. Both soloists sang well, but the choral forces earned the most attention, while Oramo held things together masterfully. The BBC Proms Youth Choir and BBC Symphony Chorus were massed together in the steep choir stalls, creating a literal wall of sound at the back of the hall. This tends to work well in the RAH, and was especially effective tonight with the quality of sound on offer. A good pace couldn’t stop the Sea Symphony dragging in places, but there were some truly beautiful moments of singing. Most of these came in the fourth section, “The Explorers”, with an exquisite semi-chorus lament “Wherefore unsatisfied soul?”, followed by the chorus and soloists affirming their commitment to set to sea. It’s not just about a pre-war obsession with sea voyages, it’s about life’s journeys and about restlessness. Yet what was most memorable was the sheer scale of everything; individual voices got lost in the fervour.

This was something completely different to last year’s First Night of the Proms – in the best possible way. While 2012 milked the patriotic spirit of an eventful year, this year’s festival opener was still British-dominated, but all about original, sometimes subtle, and exciting music. The components of the programme did feel mismatched, but the standard was high and polished, and no-one was complaining.