Well after a good bit of hunting round, this got me what I was after:
- platform: sql
queries:
- name: Pool Temperature Yesterday
unit_of_measurement: "°C"
query: "SELECT * FROM states WHERE entity_id = 'sensor.pool_temperature' ORDER BY ABS(strftime('%s', created) - strftime('%s', datetime('now'), '-1 day')) LIMIT 1;"
column: 'state'