The Baptist Union of Great Britain produced a very interesting explanation of the apology for slavery - http://bugb.org.uk/news_media/latest_news/jamaica.html

It is worth taking this into account in this debate about Ireland.  We, as Brits, may not have been directly responsible for the potato famine, we were responsible for the political and social conditions in which Ireland found itself at the time.  Remember that the same disease hit the whole of Europe (not simply Ireland), but it is only Ireland's experience that is remembered so poignantly.  One problem was the potato became the single most important staple of most of the Irish workers, whereas the main diet still revolved around butter, milk, and grain products until the early 18th century. This passage from the wikipedia article on the famine highlights its importance and how it allowed the landlords and owners to pay a pittance:

The expansion of the economy between 1760 and 1815 saw the potato make inroads in the diet of the people and become a staple food all the year round for the cottier and small farm class.
The potato's spread was essential to the development of the cottier system, delivering an extremely cheap workforce, but at the cost of lower living standards. For the labourer, it was essentially a potato wage that shaped the expanding agrarian economy

I accept that these political, economic and social conditions remain under debate, but as the controlling power (in much the same way as here in S. Wales) the British do have to hold our hands up to several mismanagement issues.