Diana and Domingo were great hosts and, even though Diana had little English, we conversed well when it was important using Google translate on my Tablet. Diana cleared a shelf in her Fridge for me to use for water and snacks. There is a small local supermarket across the road that does the most delicious fesh fruit, water etc. and a very reasonable and friendly Restaurant at pavement level under the flat which does very good Tapas etc.
Puerta Del sol, the main square of Madrid is a 5 to 10 minutes walk away, the other side of the Gran Via, Madrid's main thoroughfare.
Thoroughly recommended and I hope to stay there again.