Like the Queens' College Chichester elms in Cambridge, the Magdalen College trees were not observed to produce root suckers, though The Grove at Magdalen has long been a deer park, and any sucker growth is likely to have been cropped.
Similar to the elms at Queens' College in Cambridge, the trees at Magdalen College did not exhibit root suckers, despite The Grove being a deer park for many years. It's possible that any sucker growth has been removed through pruning.