The BBC version of the recipe has the chutney on the side, yes. But the pairing for the curry itself is plain rice.
You would typically see chatni as part of a wider Bengali spread (veg, dal, meat / seafood, rice, etc) — my Bengali friends usually relish it as the last “course” after the mains are eaten, almost as pre-dessert (it’s sweet & tangy in all its versions).
Here’s the most common tomato version (from this meal):
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From a blog (and my coin finally dropped as to where the British version of chutney comes from, as Calcutta in Bengal was their capital in India before independence):
“Bengalis are extremely fond of chutneys or ‘Chatni’ as they call it, and no meal, especially lunch, is complete without it. Chatni in Bengali cuisine is an element of transition between the main course and dessert, and not a side dish served with snacks or fries. It is served right after the fish or meat courses, along with crispy fried papad that is used to slurp up the chatni.
Bengali chutneys are of several variations, flavor, and ingredients that keep changing according to the availability of seasonal fruits. Though there are several variations, the core of any Bengali chatni is its sweetness combined with a bit of tanginess, and sometimes with a hint of hot spices.”
