what did the British by way of India do with chutney? side dish? mixed in with food? or…
Relish, mainly.
Chutney is considered a condiment. Like any Doper worth their salt, I can make chutney (papaya chutney, that is) better and cheaper at home, and since my recipe makes a ton of the stuff, I do a few things that could arguably be considered “cooking” with it. But they aren’t traditional British uses, they are just things I made up myself:
- A dip for veggies or chips made with cream cheese, chopped bell pepper, a finely minced jalepeno, and plenty of chutney
- An ingredient in deviled eggs
- Instead of pickle relish in tuna salad
- Blended with oil & vinegar or mayo for a salad dressing
I love spreading it on a slice of apple and topping with a thin slice of sharp cheddar cheese. It also goes great with toasted almonds on a baked brie.
It’s been used as a relish or condiment every time I’ve seen various people from various places use it. I think the consensus is clear. 
I wouldn’t use it in something where the chutney was going to be “really cooked”, if you know what I mean, but if it’s going to be just heated, so that you can still find the chutney afterwards, then I think it’s worth exploring.
Here’s an analogy: Some hot sauces are made to be cooked, expected to be lost in the final dish. But pico de gallo is not like that; when you add pico de gallo you’re expecting to see it and taste it for itself. Similar with chutney.
It works really well as a sweet condiment to offset a spicy hot dish. A little scooped up with a forkful of spicy is very nice.
Chutney is basically ketchup made from a fruit/vegetable other than tomato. It can be used similarly.
Oooh, I’ve been thinking about making some chutney. It’s mango season in CA, and while they’re not cheap, they’re AMAZINGLY delicious. If I happen to accidentally buy too many and need to use them up, I’ll whip up a batch.
I use chutney as a sandwich spread, especially with cheese. I plop a spoonful beside any Indian-flavoured dishes I make, like dal or curry. Like CairoCarol I mix it with cream cheese spread as a dip for veg or crackers.
Chutney is a Hindi-derived word that means sauce, just as salsa comes from Spanish for sauce. Salsa and chutney are not really interchangeable, but that is just because they come from different culinary traditions. Some chutneys are almost indistinguishable from some salsas.
When my SO’s aunt and uncle were visiting from England, and were being instructed on the art of eating fajitas, his uncle asked if we normally spread the chutney all over. He was referring to a bowl of my homemade mango salsa.
This right here is about 80% of typical British chutney usage. It’s also an essential element of the classic Ploughman’s Lunch.
Just as an aside, if you ever come across mention of a “cheese & pickle sandwich” in a British source, the “pickle” is actually chutney (even though chutney isn’t technically a pickle).
To expound further on the origin of the word, its is from Hindi word for “lick”. As in, something so tasty it will make you lick it off the plate.
In much of north India chutneys are similar to what is described upthread. But in the South, chutney is mainly fresh coconut based and very fiery.
I’d watch a cooking show hosted by a chef named Chutney.
I’m not sure I’d say that, as there is tomato chutney, and ketchups can be made from things under than tomatoes (and they originally were, first as a kind of pickled fish sauce, then as a mushroom sauce in the UK, then finally as tomato ketchup.)
It’s mostly just a type of relish, though some can be saucy, some might be chunky, some might be pickled, some might not, some might be sweet, some might be spicy, etc, but generally as a table side condiment. I would just call it a South Asian relish.