Church choirs, Traditional music

You need to check the individual church websites to see what's on the schedule. For instance, Westminster Cathedral has evensong as does York Minster. Sometimes choirs or organists can be practicing when you visit too.

Omg, our best experience was thanks to Rick's UK video. It was about the town of Wells not too far from Bath, maybe half hour. We went to Stonehenge in AM and then into Wells and toured town, Vicars Close and cathedral. We passed by cathedral again that evening and saw a lot of cars pulling up and parking. We thought it was an evening service so we asked people walking up to church and were told it was an evening boys choir practice and they invited us to come in with them as their guests which of course we did. We got to sit right up front in what I guess were some kind of choir stall chairs, can't explain but it was one of the very best experiences. I think their boys choir is world known so even if you can't do what we did, try to find out if they have a concert or sing at a church service.

http://international-eisteddfod.co.uk/

Early July

Evensong in Westminster Abbey (not cathedral, that's a different place) and/or York Minster. You sit in the choir stalls. It's a short religious service but mostly music.

In most major European cities there will be posters and handbills that announce concerts in all kinds of venues. All the places you mention will have these. You may have to do a little more hunting in the Cotswolds but you will find something I'm sure. In London, the Church of St. Martin in the Fields is known for their concerts. It's right on Trafalgar Square...as you face the National Gallery. It's the beautiful church with the tall steeple just to your right.

Dick, my mistake re Westminster Abbey. But Westminster Cathedral does have organ recitals. :)

Grab a copy of Timeout Magazine when you arrive at Heathrow. Excellent at listing all that is happening in London. When, where and what tube stop is nearby. http://www.timeout.com/london One of my favorite London chorale groups, http://www.london-concert-choir.org.uk, are worth seeing. I would also check what might be happening at St. Martin's of the Fields during your stay. http://www.stmartin-in-the-fields.org/event/choral-evensong/. Evensong at St. Bride's Fleet Street is fabulous so worth investigating if it's reopened. It was going under renovation on my visit last Fall and not open to the public. Lastly, this might be of interest to you. http://www.templechurch.com/wp-content/uploads/2014/01/Organ-Recitals.pdf

I would use the resources mentioned already, in addition to the Tourist Information Office in each town. Evensong and other church services and low-key concerts always seem to be around.

In addition to York Minster and St-Martin-in-the Fields, Evensong at St George's Chapel @ Windsor Castle has such historical significance ( look at the names of many of the most famous people in British history on the backs of the chairs in the choir stalls). Sunday Service at St Paul's or Westminster Abbey is also an option. Small parish churches may have only an organist who can be mediocre or accomplished, but the reverberations in a stone church are something I enjoy.

We are looking forward to Evensong at Wells and a service in Welsh at St David's Cathedral (Wales) in June.

In addition to the suggestions regarding websites, when you are there look at the bulletin boards outside the churches. Last Sept I was just glancing at the board outside Bath Abbey to see what kind of things were posted and realized there was an organ recital that evening. It was wonderful! Same thing again at St Mary's Church in Betws-y-Coed with a male voice choir from a neighboring town. IIRC both venues asked for a 5£ donation.