There are many hundreds of choirs whose members fall into the 'senior' category. As we get older our voices become less flexible and our range can diminish. The SAB arrangements have been specifically done with this in mind to make singing a fun experience rather than a challenge. Often there are fewer men in the choir than women, so this has also been taken into consideration.
I have sung in choirs all my life starting as a chorister at New College Oxford.
As a composer I was nominated for an Ivor Novello award for the Best Original Score for TV for my work on Sir David Attenborough's The Life of Birds.