IBM is the top tech employer at #21 and Microsoft (#34) beats out Google (#39). Soap (Uniliver @ #23) and groceries (Tesco @ #26) are sexier than working for these tech companies, I guess.
I have nothing against accounting firms (which claimed most of the top spots) but, come on Britain, there really are better jobs out there. I suspect that much of the reason stems from the number of opportunities available in tech (the UK isn't the center of the technology universe by any stretch), as well as the risk profile of the average British graduate. Big, established companies in old industries are seen to be safe bets. Tech companies...? Not so much.
I've actually seen this in a few of the companies in which I've worked, where we've had UK offices. It's not easy to recruit in the UK. In the US, people join startups (or even larger tech companies) for the reward of working in a fast-moving industry with the potential for serious upside.
This doesn't appear to be what drives the average Brit/Scot/Irishwoman, unfortunately. It's the UK's loss....