Concerns that big British businesses, such as Tesco, will be deterred from trading in Northern Ireland after Brexit have been raised in the House of Lords. Lord Kerr, the architect of article 50 which enabled the UK to leave the EU, has said the special arrangements put in place to avoid a border on the island of Ireland may be a fatal trade barrier for some companies. Under the Northern Ireland protocol, all businesses sending goods to the region from Great Britain will have to make formal declarations for the first time, with food sellers, such as supermarkets, subject to separate checks on chilled and fresh food from January. “How confident are you that GB businesses are just not going to write off the Northern Ireland market?” he asked the Northern Ireland minister Robin Walker, who was appearing before the Lords EU committee. “I am very concerned,” he continued. “Are you talking to the big stores? Are you talking to the Tescos, who have an operation in Northern Ireland but all the extra costs of this, and all the [extra] bureaucracy, may make it to them seem just not worthwhile?”. Just three weeks ago the first details of the new trading conditions across the Irish Sea emerged, with businesses obliged to complete customs, security and transit forms on all goods being transported to Northern Ireland. Walker said the government intended the new system to be “light touch” and streamlined. However, he faced further questions about the government’s preparedness, with Lord Teverson asking whether the new IT system, the Goods Vehicle Movement System, would be tested in time. And the former Conservative chancellor Lord Lamont challenged Boris Johnson’s repeated assertion that Northern Irish businesses would continue to enjoy “unfettered access” to Great British markets. Lamont argued there was a clear conflict in the Brexit protocol between article 5, which demands Northern Ireland businesses complete exit summary declarations for all goods being transported to the rest of the UK, and article 6, which promises “unfettered access”. “That is a rather awkward thing,” he told Walker, saying it was within the UK’s gift to ensure unfettered access. Walked conceded that some of the detail of the protocol had yet to be agreed by the joint committee chaired by Michael Gove and the vice-president of the European commission, Maroš Šefčovič. He also said details on the Northern Ireland border operating model, expected on Monday, would be published in the “coming weeks”.