Many valid points have been raised relating to this issue. Being a free market society, all businesses big or small make whatever decision which they believe would be in the best interest of their owners, which is the share holders in this case.
The issue is because it is a "foreign institution" and therefore possibly relocating causes constination. Don't forget every major company which sets up in a foreign country does so if there are financial incentives, and this is considered over what value you would bring to the local economy in the way of employment and other benefits.
Quite rightly it's been said that England were world leaders in various categories for manufacturing

. I also agree with miked response.
But there were additional factors I believe, where choices were made by the next generation not wanting to work in industries where their parents work for little and nothing with possibly just ill health in repayment

. Parents also agreed in this as they also did not want their little johnny/mary to follow them. London has always been seen as the place for someone to make their fortune (enter stage right Dick Whittington).
With the other countries providing cheaper labour obviously business would take advantage of this and therefore decided to locate there

,although in recent years this as been offset, only by a small degree, with some manufacturing companies setting up business here as they still saw there is a ready workforforce with a set of ready engineering skills.

UK decided to focus on the financial sector as they saw more money could be made in this, even to the point of wanting to be the centre for the Eurobean banks location. This is where specialism comes into it's own. I would say whatever government it was at the time, decided that was what the uk was good at as the Ciy of London had a long history of finance and trade and did so throughout the world and so therefore it was that other countries were left to manufacturing.

England still do have some manufacturing companies, mainly small family run concerns, but it is no way a manufacturing powerhouse.
I do not mean to digress so back to the HSBC having its roots in Asia. As the asiatic region, which is quite geographically substantial, I believe its decison to relocate, whenever that is, is more strategic than just the corparation tax issue and red tape. They would find it far more easier to take advantage of the economic growth of those various economies as Hong Kong is idealy strategically placed.