This is my wife's first year to have an allotment she has grown a number of things , one thing she has is maize , the plant are very strong and are 7 or 8 feet tall, the problem is there are no flowers on the top and no fruit, other people on the plot have much smaller plants but have a good crop, the seed has come from Zimbabwe, any ideas where she is going wrong. Many thanks.

Welcome to the site!

Moving your question to the Vegetable and Fruit forum.

Corn is a very variable crop. Depending on variety it can take 60 day to 140 days to maturity. Early varieties tend to be short like three to four feet. Late varieties used mostly for silage can reach 20 feet in height, It is also possible that it is a heat loving variety (Zimbabwe) and the English climate is too cool for good growth. It also appears to too crowded for much ear production. At this point about all one can do is to wait patiently to see what happens. It will tassel when its time comes.

As farmer Dill said, just wait, it will tassel and cobs will come.
WHAT variety did she plant?