Sometimes tactics inform the strategy (if you have particular tactics that create a strategic advantage), but usually it is the strategy that drives the tactics.
In Foreign Policy, there is a good write up of why the British methods didn't work. We have celebrated the Brits courageous fight in Helmand before. Now, it's time to adjust the tactics and re-evaluate the success in Helmand. Last week, the Brits turned over the command of the Helmand area of operations to the US Marines.
...So what did go wrong with British leadership in Helmand? What part did the U.K. play in the transformation of what was a quiet backwater of the country in 2006 into this violent quagmire which now requires a garrison of 20,000 foreign troops (twice what the Soviets deployed to the province)?
The British had deployed in 2006 with an original plan for Helmand that echoed key elements of what was to become Gen. Stanley McChrystal's strategy. Its mission was to avoid combat and concentrate on protecting the population by providing basic security and fostering development in a narrow zone of central Helmand.
But the plan was not followed...