Thanks for the advice, I cannot avoid cattle entirely as prime stretches run through their fields. Inevitably, fishing tends to involve both sitting quietly and moving silently, thus arm waving and clapping my hands - though doubtless effective - would prove somewhat self-defeating from a recreational point of view. Shouting is also taboo if you plan a trip to the river and expect to catch anything.
Don't worry, I have never again taken any form of bucket through a field of cattle. I gathered from the carefully calculated horn sweep that brushed my leg and emptied the bait bucket contents on the grass that this was indeed what they had been angling for. A well-timed, and rather neat, sidestep by his partner-in-crime made any planned attempt to salvage the contents more than foolhardy; the only consolation being that the mixture of halibut pellets and tutti frutti boilies were probably not what either had been planning on getting stuck into. In case there was any doubt my presence was no longer required, I was promptly butted impatiently to one side and a fixed angry glare from another large steer trotting over to get into the action prompted a swift retreat over the iron gate. Shortly after my departure another steer then reared up against it and suddenly slammed his forehead onto the top bar like some kind of wild buffalo. I then got accusatory glares from fellow campers who were peering over the hedge to see who had upset the 'poor cows' and had to tramp back round to my little tent (no motorhome here) via the bramble bush route.
Apparently no way to quietly share a field with a load of cattle then, at least not for any length of time without the necessary arm waving and shouting at some point, probably just as the fish are finally coming onto feed. Looks like I will have to concentrate on areas of the rivers without cattle in them come June then or risk another jab in the rear.
Thanks for the advice, I will use it. BTW if your bull hurts someone after you have put the 'Beware of Bull' sign up where the footpath crosses your field you are then liable, hence there are no signs anymore. Not much of a comfort for either party really.