Strange, if they want to extend their offer you would think they would include a sixth form. Although pupils may move for sixth form, most aspirational parents look for an independent school that goes to age 18 so they have options.
Huge demographic changes across London - drop in birth rate and families benefitting from hybrid working or being priced out of areas such as Dulwich Village to the Home Counties, including wholly or partially selective LAs. Only 15 three-bed plus houses for sale in Dulwich Village at the moment and the cheapest 3 bed bungalow is 1m. Some strong state and independent schools are left for those that remain in the area.