I asked about weaning when I saw my dermatologist (i have bad eczema and allergies to lots of things). She gave me a a list of foods that are more or less likely to cause a reaction (she also consults at gt ormond st). As follows, least likely to cause a problems: mashed carrot, swedes, turnips, green beens, parsnips, cabbage, broccoli, cauilflower, stewed apple or pear.
next group: moderate likelihood: potato, oats, wheat, rice, chicken, turkey, beef, lamb, pork, fish, tomatoes, citrus fruit, strawberries, raspberries, marmite, honey.
next: may cause severe reaction: cow's milk, goat's milk, cheese, yoghurt, eggs, kiwi fruit, peanuts, banana, avocado, peas, lentils.
She said introduce 1 food at at time, starting with first group. and not before 4 months, preferably 6 months