Richard North has answered my question, stating that neither he or Helen Szamuely has been paid for their efforts with the Bruges Group. However, EU Referendum Blog still doesn't carry any disclosure of their association with the Group for a Europe of Democracies and Diversities (the European Parliament caucus that includes UKIP) or the Bruges Group respectively.
This may seem petty, but can anyone else imagine the hyperventilating spasm of rage the Right would work up if - say - a blog calling itself Euro Referendum was to set up, claiming to - say - "discuss the UK referendum campaign", operated by the director of research of the Britain in Europe campaign and the former head of research of the Party of European Socialists, without making any mention of their former lives? They'd be bleeding from the eyes with loathing.
Total disclosure, for the commenter who saw fit to accuse me of being funded by the "Yes Campaign": I have never received any financial or other consideration from anyone in relation to this blog. My only partisan affiliation is that I am a member of the Liberal Democrats, a fact repeatedly alluded to in posts on this blog since November 2004 (when I joined) and also in my campaign reports on General Election '05. It would be difficult in the extreme to receive money from the "Yes Campaign" because it doesn't exist yet. My income originates from my day job on Mobile Communications International magazine, the world's longest running journal for the mobile industry. I recently refused a trip to San Diego funded by Qualcomm, Inc. on ethical grounds. I do not and have never claimed impartiality (see the strap line at the top of this blog).