The question asks which of the given methods is a "teacher-centred" method of teaching mathematics. Let's evaluate the options one by one:

• Group Discussion Method: This method is student-centred, as it involves active participation and collaboration among students to discuss and solve problems.
• Problem Solving Method: This is a student-centred approach where learners engage in solving mathematical problems, fostering critical thinking and self-discovery.
• Lecture Method: This is a teacher-centred approach. In this method, the teacher delivers a talk or presentation on a particular topic while students listen and take notes. The focus is on the teacher's delivery rather than on student participation.
• Heuristic Method: This method is student-centred; it encourages learners to discover and learn through curiosity-driven exploration and experimentation.

Considering the above explanations, the Lecture Method is indeed the teacher-centred method among the options provided. In this approach, the teacher is the primary source of information and control, focusing more on delivering content rather than engaging students in interactive learning.

Therefore, the correct answer is Lecture Method.