1. Introduction

2. Data
2.1. The Gaia-ESO survey
2.2. The iDR5 sub-sample used in this study

3. Methods
3.1. DOE
3.2. Getting narrower HR21 CCFs
3.3. Quality control
3.4. Error budget

4. Results
4.1. Double-lined spectroscopic binaries
4.2. Triple-lined and quadruple-lined spectroscopic binaries
4.3. Locus in the colour-magnitude diagram and comparison to Gaia
4.4. Comparison to Merle et al. (2017)
4.5. SB2 detection rate
4.6. Mass-ratio distribution

5. Summary and conclusion