My tassles are brown!

Check the ripeness with a fingernail https://www.youtube.com/watch?v=qjtM0wGGSXA

The one thing I find with growing mine in the greenhouse is that all the cobs get fully pollinated. When the tassels develop pollen I tap the main stem with a cane to release it onto the silks. Some of the pollen falls onto the leaves below but as I generally tap them until no more is released, this eventually gets onto the silks that develop a bit later. I can't grow them outside because it gets very windy here and the pollen just gets blown away.

Been an amazing year so far for Sweetcorn and mine have matured a few weeks or more earlier.
Normally get three cobs on almost all of them and a few with four.
This year they are all producing four cobs with just some later grown ones that have so far just had the normal three cobs and looks like they also will all be a good size.

I always tap each plant as I pass by each day to spread the pollen.
But planting them in blocks together is the trick as that then spreads the pollen over the crop and not over other parts of the garden.
Not ever had wind problems with sweetcorn, but they seem happy in a gentle breeze. They are in a sunny position and semi- sheltered.
I have always built up the soil around their 'triffid' feet roots, once they are about five feet, so they do not bend over.

Please tell me what variety you planted!

Golden Bantam.
Grown that variety successfully for many years.

You will be OK with Golden Bantam in the south of the UK but in the north it has not been a good variety for me.  Best results have been with Lark and this year Zuccherino from Seeds of Italy has been great, but an exceptional year.