That would have been Call Changes. The conductor (that's the ringer who was doing the shouting) changes the order the bells are ringing in by calling out the change to be made.

Run that past me again.

OK, the bells start off in order
1-2-3-4-5-6-7-8
The conductor wants to change to order to
1-2-4-3-5-6-7-8
In other words, 4 is to be after 2 instead of after 3. The call is simply "4 to 2" - it does what it says on the tin.

OK ... but also 3 is after 4 instead of after 2.

Yes, that's right. So the call could have been "3 to 4" to achieve the same result.

Isn't that a bit confusing

Not really. The convention is that the conductor consistently calls the same way. Also towers tend to favour one or the other

Which one is better

Now there's a question. Many pub-hours have been spent in debating the relative merits of each. Ultimately, it doesn't make much difference. My personal preference is "3 to 4" - which, ironically, is not the way used in my local tower.

Hang on, I've just noticed. In that call above, 5 ends up after 3. Couldn't the call have been "5 to 3"?

No, as that would give
1-2-3-5-4-6-7-8

Ah yes. So how does the 5 know to start following a different bell?

That's the catch. The ringers have to pay attention to know what to do. It's easy enough to start off with, but as the order gets messed around it gets more difficult. Generally, if you know the two bells in front of you, you can work it out.

Sounds complicated

It can be - even experienced ringers can come unstuck. And the conductor, of course, needs to know the order of all the bells (or what the order should be). That can be even more complicated.

So to change the order from
1-2-4-3-5-6-7-8
The conductor calls something else? Like "5 to 6" or "6 to 3"?

Yes. That would give
1-2-4-3-6-5-7-8

So basically you just swap pairs of bells over until you get bored?

Pretty much - ideally you swap them into different orders then back into
1-2-3-4-5-6-7-8
before you get bored.

Are there any particularly musical combinations?

I was hoping you would ask that.
1-3-5-7-2-4-6-8 is knows as Queens (I'm not sure why)
1-5-2-6-3-7-4-8 is known as Tittums (because it sounds "te-tum-te-tum-te-tum-te-tum")
Go find a piano and try them out
Oh, and, on five bells
1-4-2-3-5 is (unofficially) known as Weasels (you can work out why for yourself)

Is the paint dry yet?