The LAS regularly invites professional astronomers to it's meetings to give talks. Here are some of these speakers and their subjects over the last few years:

Dr Francisco Diego	Dept. of Physics & Astronomy, University College , London.	Eclipses of the Sun.
Dr Gerry Gilmore	The Institute of Astronomy, Cambridge.	New Results from Space.
Dr Steve Fossey	University of London, Mill Hill Observatory.	Measuring the Hubble Constant. The Interstellar Medium.
Dr Steve Miller	Dept. of Science & Technical Studies, University College, London.	Astronomy and the Media.
Dr Peter Williams	Dept. of Physics, Queen Mary & Westfield College, London.	Neutrino Astronomy.
Dr Ralph Wijers	The Institute of Astronomy, Cambridge.	Gamma Ray Bursts & What They Might Be.
Dr Mike Irwin	The Institute of Astronomy, Cambridge.	Satellite Galaxies of the Milky Way.
Dr Robin Catchpole	The Institute of Astronomy, Cambridge.	Stellar Evolution.
Dr Cathie Clarke	The Institute of Astronomy, Cambridge.	The Formation of Stars. The Formation of Planets.
Dr Margaret Penston	The Royal Greenwich Observatory, Cambridge.	The Hipparcos Project.

Dr Jasper Wall	Director of the Royal Greenwich Observatory, Cambridge.	The Universe in a Glass of Water
Dr Mike Lancaster	University of London, Mill Hill Observatory.	The Work of the Magellan Probe at Venus.
Dr Tony Ridley	The University of Middlesex - Dept. of Science.	Measurement in Astronomy.
Dr Robin Catchpole	The Institute of Astronomy, Cambridge.	Achievements of the Hubble Space Telescope.
Dr Iain Nicolson	University of Hertfordshire.	Our Star the Sun
Dr Chris Kitchin	University of Hertfordshire.	Black Holes - How they Originate.

Many other non professional astronomers (amateurs) and often experts in various fields have contributed to the LAS programme over the years. Some of these have been associated with other astronomical societies, others have been connected with organisations like the British Astronomical Association to which the LAS is affiliated.