Baroque pop

Baroque pop, baroque rock or English baroque, often used interchangeably with chamber pop/rock, is a style of music originated in the mid-1960s that brought elements of classical music into the writing and recording of rock 'n' roll songs. Practitioners of the style utilized instrumentation not traditional to rock such as harpsichord, oboe, cello and french horn. Baroque pop's highest popularity occurred before the introduction of the synthesizer or sampler, so "real" instruments are heard on the recordings, usually played by session musicians. Baroque pop may be distinguished from progressive rock which uses classical instrumentation by its generally simpler song structures closer to standard pop song writing, and also by its more mainstream lyrical content as opposed to the more conceptual lyrics associated with progressive music. Baroque pop is similar to sunshine pop in subject matter, but with a more melodramatic and "darker" edge.

Source : http://en.wikipedia.org/wiki/Baroque_pop