string quartet + chamber orchestra + symphonic orchestra. Why?

Question

In “Fantasia on a Theme by Thomas Tallis” by Vaughan Williams, we see a string quartet performing alongside a chamber orchestra of about eight people and a full-scale symphony orchestra. I wonder why that would be necessary. Wouldn't a full symphony orchestra have been able to handle the entire performance on its own? Is this a novelty, or is it a common practice in classical music production?

Answer 1

Wouldn't a full symphony orchestra have been able to handle the entire performance on its own?

No. One possible point of this disposition, as Aaron mentioned, is to create a dialogue with three participants: an orchestra, the chamber orchestra, and the string quartet. This could well be a nod to the popularity of "polychoral" works in Tallis' day; in particular, Tallis is famous for having produced a piece for eight five-voice choirs.

Keep in mind that the piece was composed for performance in Gloucester Cathedral, so Vaughan Williams would have had in mind the significant spatial separation shown in the video rather than the relatively close positions that would be required on most concert stages. Perhaps most critically, a listener in the cathedral (and even in a concert hall) would have a far greater awareness of the spatial arrangement of the forces than is possible to convey in the stereophonic soundtrack of a video recording.

With this context, let's look a bit at the score. At the opening, the three groups are playing the same notes. In this section, therefore, your comment on Aaron's answer is correct:

all the goups' sounds get mixed together and what we get to hear on our end is something that would otherwise be coming from one large orchestra.

But six measures before F, the chamber orchestra separates from the group and begins an antiphonal dialogue. This lasts until I, when the solo viola plays, answered by the chamber orchestra, then both orchestras, then, at J, a passage for the solo first violin, eventually joined by the rest of the solo quartet, then a brief passage by the chamber orchestra, then both orchestras, then, at L, the quartet again.

At M and N, things get more complicated: instead of antiphonal call and response, or echoes, you have the solo quartet playing continuously and the chamber orchestra punctuating their passage with just a couple of chords. Then the chamber orchestra takes up the main role, with the large orchestra playing a single quarter-note chord in each measure while the string quartet plays three eighth notes in an ascending figure. This sort of interplay continues, becoming denser and more complex, until four before Q, where again everyone is in unison.

It would certainly be possible to write this out for a single orchestra with each section sometimes splitting into three parts, but it would be very confusing -- for the players as well as for the conductor -- so "clarity of the written score" is certainly a major consideration, but it's not the only one. Far more important is the listener's experience of the piece as a composition for multiple string choirs that respond to one another, echo one another, and complement one another.

The most significant reason for this disposition of forces, however is probably that Vaughan Williams decided (or was asked by the commissioning organization) to write a polychoral piece before he even started to compose it. It may be no accident that it was first performed with Elgar's Dream of Gerontius, a work for "double chorus with semichorus": the commissioning organization was the Three Choirs Festival

Is this a novelty, or is it a common practice in classical music production?

Polychoral music has been common at least twice. As noted, it was common in the renaissance, especially for particularly festive, grand, or solemn occasions; this persisted into the baroque period and beyond, albeit somewhat less frequently: Bach's St. Matthew Passion, for example, is written for two choirs and two orchestras. There was certainly a revival of interest in the practice during the late nineteenth century and early twentieth century, at least in England. William Walton's Belshazzar's Feast, for example, calls for two choruses plus a semi-chorus, a full orchestra and two brass bands.

Answer 2

As a starting place, consider a violin concerto. A full symphony orchestra could certainly handle the performance, but there is still a clear call for one violin to act as a separate entity from the larger ensemble. Thus, rather than scoring the piece for "just orchestra", and embedding the solo part along with everything else — and similarly, having the soloist perform sitting as part of the orchestra — the score calls out the solo part specifically, and the performance places the soloist separately from the ensemble.

Similarly with the Fantasia. Vaughan Williams wants certain groupings of instruments such that each as a life of its own, so to speak. Although it could be handled entirely by one sufficiently large group, it gives clarity to the written score as well as to the performance to treat each group as an entity of its own.