Four went into making a curd which was enough to yield three and a half small jars, which is plenty because it doesn't keep for long. I've had bad luck with curds in the past. My first attempt at lemon curd (late one night after a shift waitressing because a guest wanted it for breakfast) was a disaster because the recipe (Sophie Grigson, and I've looked askance at her books ever since) in what I hope was a miss print, omitted the lemon juice from the lemon curd. I didn't know any better. Since than (thanks to Claire MacDonald and her lemon curd pavlova) lemon curd hasn't presented a problem - even if it's a bit of a bore to make. I've tried, and disliked, orange curd, and once made an apple curd which again I really disliked.
The good news is that bergamots make a great curd. It's a lot like a lemon one, but with an aroma and flavour that suggests something like sherbet. The extra bitterness is discernible, but welcome, and when I took the half jar to work and made people try it the result was really positive (words like delicious were thrown around). It's different enough from anything you can buy to make it worth the effort of making too.
The recipe is basically the one from Ocado's website but uses the JUICE (turns out this matters, 23 years, I haven't forgotten) and zest of 4 bergamots (the original uses 2, along with 2 Amalfie lemons) 250g of granulated sugar, 100g of butter, 3 eggs and a 4th egg yolk. Heat the butter, sugar, juice and zest until butter and sugar have melted, but don't allow to get to hot. Whisk the eggs and extra yolk together, and add to the mix whisking all the time (now us not the moment to get a sweet citrusy take on scrambled eggs, which is why the temperature shouldn't be to hot), carry on whisking until the mixture thickens to something your happy potting. Pot - in sterilised jars. Opinion about how long it keeps seems to range from a few days to 4 weeks. I'm hoping 4 weeks.
That leaves me with one lone bergamot, it's destined for more gin and tonics. The final verdict is that they're well worth playing with if you can get your hands on some.