Gas disc radius as a function of dust disc radius, using α_ν = 10⁻³ and the Pic21 photoevaporation prescription for different cluster ages. Triangles show discs which have retained more than 0.1 M_⊕ of dust, but whose gas accretion rates are lower than 10⁻¹² M_⊙ Yr⁻¹. These are the discs, corresponding to 15% of the initial disc population, in which photoevaporation has opened up a gap, with a detectable amount of dust is retained outside the gap. Grey markers show observational measurements from Long et al. (2022). Grey lines show the R_gas = R_dust (solid) and R_gas = 4R_dust (dashed).