Meanings of natural trumpets in English

A revolutionary development revealing that Sullivan had always secretly craved performance on natural trumpet and harpsichord?

The performers were described as a "baroque trio" and originally listed as natural trumpet, soprano and harpsichord.

The natural trumpet was used very much as a fanfare instrument, and was used in conjunction with percussion and woodwind instruments for ceremonies.

For grand heroic effect, valve trumpets cannot replace the natural trumpets with slides, which are now only to be heard in this country.