This is more of a recommendation for when the plants are much larger, getting ready to produce corn. Corn has pollen-producing flowers at the top of the corn plant (tassels; male flower structure) and the silk that is at the end of each ear of corn (female flower structure). Corn in a field is wind-pollinated; in a container, you will need to help out. When the tassels become dusty, they are releasing pollen. Have a plastic bag (gallon zip-seal type is good) and knock the pollen into the bag each day, store some place cool until you need the pollen. When ears are producing silk, brush a little of the collected pollen onto the silk each day until the silks go brown and the ears are clearly getting larger.
This will increase your chance of getting some corn off your plants. TBH, this is the first time I have heard of growing corn in a container, so I am excited to see how this works out for you! Maybe it is more common in UK gardens? Good luck!
