Why didn't my aubergine plant develop any fruit?

From what I can gather, you probably needed to pollenate the plant manually with a small soft paintbrush, the fruits would not have set simply because the flowers did not self pollenate.
Next time, when the flowers are in full bloom, get a small soft paintbrush, like an artists watercolour brush or similar, and go from flower to flower gently brushing around the center of the blooms, stamen? stomata? it's late and my brain forgets! lol.
Basically transfer polen from flower to flower getting it all mixed up, not forgetting to go back over the first flower you brushed when you're done.
This is all theoretical of course because I can't stand aubergines so have never grown them! lol, but the thoery is the same for lots of plants, it's a process that would normally be carried out wind or by the insects that are lacking in your greenhouse, bees, moths, butterflies, wasps etc.

Hope that helps, better luck next time eh?

Regards,
Stewart ;-)

Thanks very much for that! Better luck next year.

Hi, I grew lovely aubergines (Black Beauty) in the greenhouse last year, and did exactly the same this year, but got same results as yourself. I think it has just been down to the weather. I didn't pollinate the flowers myself last year, the flowers and fruit developed by themselves, just fed weekly with general tomato/cucumber/pepper type liquid feed. Perhaps next year...........