1. Introduction

2. Data analysis
2.1. Cluster sample
2.2. XMM-Newton data and processing
2.3. Emission-measure profiles
2.4. Gas density and gas mass
2.5. Validation using hydrodynamical simulations

3. Stellar fraction

4. Results
4.1. Weak-lensing halo masses
4.2. Mgas-T relation and gas mass fraction
4.3. Stellar fraction
4.4. Gas distribution

5. Discussion
5.1. Systematic uncertainties
5.2. A generalised hydrostatic bias?
5.3. Comparison with previous measurements
5.4. Comparison with numerical simulations
5.5. Implications for cosmology

6. Conclusion