Historic Spanish organs are unique in (normally) having divided keyboards, so you can draw different stops for the treble and bass halves, and can therefore play treble or bass solos playing the accompaniment on the same manual. In 2019 I was allowed play the enormous baroque organ in the 12th century fortified church of San Nicolás in Pamplona, by kind permission of the sacristan—only for 20 minutes as it was almost time for mass, and then the church would be closed.
A week or so later the organist of Burgos Cathedral allowed me to play the historic Organo de Cabezón in the Chapel of the Constables. I had met the organist the previous time I was in Burgos, in 2011, but he could not allow me to play then as it was a Sunday and another mass was about to begin. This time I made enquiries at the cathedral reception and they contacted the organist for me. He remembered me from 2011(!) and made arrangements to meet me in the cathedral the next afternoon, also a Sunday. In the chapel he opened a secret door in the choirstalls, and we went up stone steps inside the wall to a little room where the console was behind the organ case. It is the oldest organ in the cathedral, built in 1530 by Fernán Giménez de Vitoria, who was the master of the organs in León cathedral. It is the oldest and best preserved renaissance organ in Spain, with a single manual of 45 keys, 8 pedal keys, and 15 divided stops (519 pipes). The tuning is ¼ comma meantone. I played some Tientos by Cabezón I had brought, for about 45 minutes. I didn’t want to keep him any longer as he had played for four masses that morning. I thanked him warmly for the experience and he said he was delighted to welcome someone who appreciated the instrument. I wish I could remember his name. Also in Burgos Cathedral in the chapel of San Enrique there is a small baroque organ built in 1674 by an unknown builder, restored in 1999 by Gerhard Grenzing of Barcelona.
In Castrojeriz, in the church of St John the Baptist, there is a a medium sized baroque instrument with a single divided keyboard and plenty of reed stops. The hospitalero at Albergue Ultreia obtained permission from the priest for me to play. I played the entire repertoire of pieces I had brought, including Aguilera’s Ensalada Obra de 8º tono alto which sounded splendid. There is a fantastic looking organ in Los Arcos but I could not contact anyone who could let me play. I was refused permission to play a small chapel organ in Pamplona Cathedral. And in the Monastery of Santa María Real de las Huelgas I was told that only the king could give me permission to play and this might take several months!
On the Primitivo I met the organist of Lugo Cathedral who showed me the two organs in the choir gallery and allowed me to play there also.