The owner of Cafe Citoyen - and those drinking there - were very helpful even offering to put a Vegan meal together for me during evening hours as it is a daytime food place and more geared up for Vegetarians
So I can only vote on his helpful attitude, and wished after a bad experience I had accepted his offer!
Central Lille (perhaps especially in quiet August?) is not very easy for Vegans to find a restaurant catering for them in the evening. I also tried to find a non Vegan place able to cater for both my Vegan diet and my partner's diet, - he eats meat - and on this occasion failed (Indian restaurant). Next time may try Pizza without cheese or Le Baldakin, (had lived on Arabic food in Paris so looking for change), or here daytime, or lunch at la Source etc.