Charles Trevelyan was a fierce advocate of laissaiz faire economics.
http://www.historyplace.com/worldhistory/famine/hunger.htm
The reason that so many food ships were leaving Ireland laiden with food was that, in the absence of any attempt by the government to purchase this food (thus horror of horrors, intervening in the precious free market) it was far more profitable to sell it on the overseas market than distribute it amongst starving Irish labourers.
Trevalyan advocated a free-market solution to the crisis that involved as little intervention as possible and hoping beyond hope that charity would be enough to cover the shortfall. He, and all the other free-market fanatics, were catastrophically wrong and people died as a result.
Just out of curiousity, if you were Trevelyan, how would you, presumably a firm believer yourself in free-market economics as the British Whig government of the 1840s and 50s were, have solved the crisis? More libertarianism, or by decisive government intervention?
LOL!
Let's consult your source:
"As a devout advocate of laissez-faire, Trevelyan also claimed that aiding the Irish brought 'the risk of paralyzing all private enterprise.' Thus he ruled out providing any more government food, despite early reports the potato blight had already been spotted amid the next harvest in the west of Ireland. Trevelyan believed Peel's policy of providing cheap Indian corn meal to the Irish had been a mistake because it undercut market prices and had discouraged private food dealers from importing the needed food."
So this is the scenario:
John Peel temporarily revoked the protectionist tariffs that kept cheap Indian grain from being made available to the Irish market.
Trevelyan was worried that the inflow of all this cheap Indian grain in Ireland would hurt the ability of the landed grain growers of the UK to keep their prices artificially high.
So Trevelyan moved to put back the protectionist barriers in order to keep cheap Indian grain off the market, so that UK grain prices could remain artificially high.
You and the author of your source clearly do not understand what "laissez-faire" means.
A true laissez-faire policy would have been to allow grain merchants from any nation to sell their wares in Ireland at any price they wanted, whether or not it hurt the profit margins of protected English land barons.
You and your source have inadvertently confirmed that intervention slaughtered the Irish, when free markets could have saved them.