Now see this excerpt from the letter he is criticising:
From Melvyn Bragg's letter you might think that, whilst he is opposed to Israel because of "continuing illegal settlements in the West Bank, the siege of Gaza, the detention of Palestinian children, and the murder of nine aid workers on the Mavi Marmara", he is against boycotts in principle. But from an earlier letter of Bragg's to the Guardian back in 2005 we can see that Lord Bragg doesn't actually do principle:
So he doesn't want a boycott of Israel because he likes Israel. What is interesting is that now he can't bring himself to list those things he likes about Israel any more. Either that or the Guardian's letters editor decided that any Israel apologetics would spoil the message.