begun ( first Monte Estoril that in 1898 had some hotels ans casinos- like Grande Casino Internacional, Grande Casino Português, Stranger´s Casino, and others .Some english people lived there and english people go there at that time for holydays.
The Estoril( was named Santo Antonio do Estoril) as we know today wass born some time later- after 1915.The grand openning of Casino Estoril was in
1931.
I think the information of J.Benedict is correct