Tough ask given the current environment. Most size players are coming through banks, but that is a semantic argument. No firm is going to do it unless the OP is a customer. Most of these firms have touchpoints in Europe that the OP calls home. Bloomberg has many of the contact info and some trading desks and the HR department names and contact info. Some firms, like AQR still allow walk-ins. London, Paris, Dublin, and Frankfurt are pretty common office locations - again their websites or bloom. Bloomberg DMS can get you many of the people you want. When you want to share more we all may be able to help more. Lots of people on this list have come from your target firms - no guarantee of help.