He was simultaneously knocked out, felled, dazed or just plain injured, depending on which report you read about the Respect MP George Galloway being hit on the head by an anti-stress ball last week. But black-affronted is one thing he most certainly would have been, given the fact that he was in full oratory throttle at the time of his facial bruising, which occurred when he was campaigning for membership of the London Assembly at the top of an open-topped bus in Central London ahead of Thursday's London mayoral elections.

The ball had been hurled from an office window situated higher up than he was, and its velocity was such that it caused the feisty 53-year-old Glaswegian MP for Bethnal Green and Bow to be treated by paramedics. It left him with metaphorical egg on his face in the form of a purple blemish on one temple where the ball struck, and an additional bump on the other side of his face when the force of the ball made him hit his head against the side of the bus.

Who would have believed an innocent-looking pale blue rubber ball could cause so much physical, and doubtless emotional, angst?

The psychological damage to Mr Galloway will surely be difficult to quantify, and is at direct odds with the original purpose of the soft, soothing device - which was invented for the very purpose of relieving stress.

Clearly, it was no use whatsoever in calming the distress of the 32-year-old perpetrator, an office worker who had been subjected to the noise of Galloway's enthusiastic electioneering through an old-fashioned hand-held loudspeaker. Given the applause that reportedly echoed around Holborn following the hit, using the ball to vent anger clearly went down a bomb.

In order to reassure us of their bona fide credentials, modern manufacturers claim that anti-stress balls were invented back in ancient times for a variety of medical uses, including treating arthritis and rheumatism, improving circulation and in helping us to focus during meditation. But they really came into their own in the UK during the 1980s with the creation of the yuppie and the rise to fashionable notoriety of the high-powered, high-earning city worker who toiled as hard as he played, went to wine bars, typically wore red braces and carried an oversized Filofax. Galloway, incidentally, was wearing designer sunglasses at the time of the assault.

So at least he can take comfort in the fact that he only had to suffer the indignity of a smack from an inert tennis-sized ball. It could have been banana or apple-shaped, or worse. Or it might have been a chrome bullet wrested impatiently from a Newton Swing, or even a plastic Tamagotchi virtual pet - all stress-busting desktop items that were once regarded as the ultimate status symbols but which have largely become representative of 1980s ostentation and the "greed is good" work ethic.

In super-stressed Japan, however, they are pushing the envelope even further with the Eternal Poppety Pop, the electronic equivalent of bubble-wrap, which is the latest gadget to be invented in the race to calm overstressed executives. Two million of them have been sold since it was launched at the end of last year.

Lest we start to believe stress is a thing of the past in the UK workplace, however, manufacturers are investing heavily in the user-friendly, organically-shaped balls by incorporating new technology into them. Vibrating and even viral balls are now de rigueur. These have an embedded transmitter and receiving chips that can communicate the levels of stress experienced by the user.

What a pity they haven't gone into production soon enough for Mr Galloway's assailant. Otherwise, he might have been able to sue.