As a grain farmer I cannot imagine what kind of farmer is worried about the wall clock. For us, the only thing that determines if we work or not is the weather. Maybe the only advantage I have noticed is that the parts dealership is open an hour later if we have a breakdown. However, we're also not yet done for the year and won't be before we go back to standard time, so that falls apart for our late season work anyway.

Further, if the UK is anything like my country, only ~2% of the population are farmers, so even if they did all object the 98% wouldn't care and move forward anyway.