Chris Dercon’s departure as head of Tate Modern, to become director of Berlin’s Volksbühne theatre (but not before 2017), comes at an awkward time for the Tate. It’s been only a few weeks since the resignation of Tate Britain’s director Penelope Curtis, who announced her move to Portugal’s Calouste Gulbenkian Museum after a bruising year of bad press, in which Britain’s newspaper pundits groused incessantly about Curtis’s unconventional programming (See Penelope Curtis Leaves Tate Britain for Calouste Gulbenkian Museum after Highly Criticized 5-Year Tenure and Chris Dercon Leaves Tate Modern To Direct Berlin’s Volksbühne Theater).

As the BBC’s arts editor Will Gompertz suggested, while losing two directors in two months might merely be regarded as bad luck, Dercon’s exit will be seen as a blow to the Tate. Between Curtis’s resignation and Dercon’s, others have been inclined to pin the blame on the Tate’s head, Nicolas Serota: writing in the right-leaning Spectator on the problems of Tate Britain under Curtis, Jack Wakefield declared that “if her reign has proved a disaster then questions should be asked about who appointed her. The culprit is Sir Nicholas Serota.” Wakefield goes on to argue that “Serota and his internationally focused trustees should not control the position” of appointing Tate Britain’s director.

Conservative commentators have long had it in for Serota—not least for what they saw as his championing of contemporary art and his apparently unfettered influence over the British art establishment—but have had to grudgingly concede the runaway success and popularity of Tate Modern since its opening in 2000. (See MoMA Curator Klaus Biesenbach Should Be Fired Over Björk Show Debacle).

Yet Wakefield’s complaint touches on what is more than anything an existential problem for the Tate, a problem that even someone of Serota’s skill and tenacity may find hard to overcome: it is starting to dawn on many that there’s an inherent problem in the way the two main branches of Tate are split between modern and contemporary international art at Tate Modern (which includes, but isn’t restricted to, British art), and Tate Britain’s restricted focus on only British art, from the 16th century to the present day.

Tate Britain struggles to define what it does and why people should want to visit it

This wonky partition has bothered commentators ever since the old Tate Gallery became Tate Britain and Tate Modern in 2000. Now, as Tate Modern continues to roar ahead, looking forward to the opening of its huge new extension in 2016, it accentuates Tate Britain’s difficulty in defining what it does and why people should want to visit it. Unlike Tate Modern, which dominates the cultural offering of contemporary and modern art in the capital, Tate Britain finds itself in close competition with the National Gallery, the National Portrait Gallery, and the Royal Academy for pre-20th century art. And not being located near to the tourist hotspot of Trafalgar Square doesn’t help.

Tate Britain’s troubles are really the product of the complicated and fudged status of Tate’s cultural remit; starting out as a collection of purely British art in the late 19th century, the Tate Gallery then became responsible for showing and collecting “modern foreign art,” while continuing to acquire British contemporary art throughout the last century to today. Concentrating on “British” in its old gallery building has only served to accentuate its isolation from the wider culture of contemporary art.

Tate Britain’s status as the national institution for British art becomes increasingly anachronistic

The relationship between Tate Britain and Modern, then, is really about what importance we give to old art and the concept of a national culture; and as it turns out, most people are more interested these days in the concept of internationalism and the culture of the contemporary, than what appears to be the stuffy, out-of-date world of narrow-minded nationalism; which is why almost 5.8 million visitors flocked to Tate Modern in 2014, and barely a quarter of that number made it to Tate Britain.

By contrast, the older, grey-haired generation of art lovers and international tourists made up the 6.4 million that headed for the National Gallery, with its more pluralistic, uncontroversial offering of old world classical and pre-modernist artistic charm.

So Serota has always had to work with the cards he’s been dealt, which is an uneven historical collection and Tate Britain’s overlap with competing institutions. His vision has seemed fixed on developing Tate as a world-beating international art institution, and focus on Tate Modern rather than worrying too much about unscrambling the institutional and cultural confusion of Tate Britain. But fifteen years after it was split out, Tate Britain’s status as the national institution for British art seems increasingly anachronistic.

Future of cultural policy in the UK is uncertain

And while Curtis’s and Dercon’s departures may just be bad luck and coincidence, both come at a time when the future of cultural policy in the UK is uncertain: in a week’s time British voters will be electing a new government, and the outcome is anyone’s guess.

Tate, like all the big British museums, has had to deal with swingeing cuts to its government funding under the current coalition of Conservatives and Liberals. But taking a look at the three main parties’ election manifestos, it’s clear that no party is making any promises about increasing funding for national museums (see As the UK Gets Ready for General Election, What’s in It for the Art Industry? ).

Meanwhile, alongside funding cuts, the next parliament will likely be overshadowed by the question of national devolution, with Scotland’s Scottish National Party continuing its campaign for further transfers of power and money away from UK central government, after losing the referendum on Scottish independence last year.

In the politicking over devolution, the question of what is meant by “Britain” is set to become a contested issue, and it’s not too farfetched to expect that the question of which institutions get to hold which works of art in their collections might soon be up for grabs.

Where next for Tate?

Faced with cultural uncertainties and funding troubles, one can see why Dercon and Curtis may have been happy to head for the door. Dercon’s move to Berlin parallels Neil MacGregor’s exit from his long tenure as director of the British Museum, to take a job advising the German government on the development of Berlin’s ambitious new arts venue, the Humboldt Forum (see British Museum Director Neil MacGregor To Step Down at the End of the Year).

MacGregor is 68. When the new Tate Modern extension opens, Serota will be 70. Having turned Tate from a wobbly national museum with a patchy collection of old and new into a world-class institution of contemporary art has been Serota’s enduring success. But what it means to have a British gallery of British art has always been an incurable problem, and beyond even Serota’s powers to solve, since it goes to the heart of how we conceive of artworks, their history, and their relevance to a society as fragmented and diverse as Britain’s.

It might not quite be time for Serota to leave the Tate, but it might be time for a very big, very public discussion about what kinds of art museums our not-very-United Kingdom wants or needs.