If you are a resident in Spain and need to apply for a Spanish police certificate this is the quickest route on how to do it.
Certificado de Antecedentes Penales = a certificate of any criminal convictions etc - like the CRB checks in UK
Download the 3 page pdf form from the Spanish Ministry of Justice here http://www.mjusticia.es/ use the search box for modelo 790.
I found the easiest route is to take an ida y vuelta (return) RENFE train from San Fernando Bahai Sur to San Bernardo (the last stop before Sevilla Santa Justa). It is like a metro station underground.
Fill in the details, including the reason why you need the certificate. Take it to any bank and pay el importe 3.47€
Make sure all 3 pages are stamped by the bank. They keep 1 page.
The nearest Ministerio de Justicia is in Sevilla:
GERENCIA TERRITORIAL DEL MINISTERIO DE JUSTICIA EN ANDALUCIA
SEVILLA (Cádiz, Ceuta, Córdoba, Huelva, Sevilla)
Plza. de España, s/n. Torre Norte, 2.º, 41013 SEVILLA
Open 9am-2pm on weekdays
Go to its exact location on google maps here and use the 'get directions' facility to Plaza de España. The walk should take 15minutes at a stroll.
Take a moment to take in The Plaza de España that of Seville's most easily recognised buildings and the epitome of the Moorish Revival in Spanish architecture.
Then go to El Torre Norte (the north tower.. you know which way north is right??) and see the door with a sign that says GERENCIA TERRITORIAL DEL MINISTERIO DE JUSTICIA. You cannot miss it because there are lots of folk from various countries and ethnic background milling around looking worried. Do not be alarmed by the queues and general mahem downstairs!!!
Go up to the second floor (segunda planta) and the door marked Certificado with your modelo 790, passport and Certificado de Registro de Ciudadano de la Unión (and photocopies of both), or whatever residency documents you have.
They look you up on their system and print the certificate (that states you do or do not have police record), get you to double check it then get it stamped in the next office by a notary type bloke.
By the way if you need to get an official sworn translation (to/from Spanish to English) I used:
Carolina Balsa Cirrito
TRADUCTORES E INTÉRPRETES JURADOS
Traductores & Intérpretes Jurados
Telf: 956 54 39 37 // Fax: 956 05 01 34
Móviles: 636 34 14 79 // 658 99 82 36
Thanks to the various people who gave me advice on this subject including Carlos and Linda, TonyT & Juan Antonio of Temple Cambria.