What is the fine-grained topic of the following text: Peggy Ashcroft and John Gielgud brought to the stage a presence enigmatic, nuanced, deep and yet brimming with an undercurrent of intensity, of the emotionally driven heartbeat driving their characters, and which could be perceived as an undeniable tension alive with portent. Only return the topic.
The acting skills of Peggy Ashcroft and John Gielgud