Complex sentence: Phantoms trials were held on Hermes in 1969-70, in Min of Defence, Dennis Healy's views the carrier could operate the most modern aircraft, but in too small numbers to be effective.
Split into simpler sentences: Phantoms trials were held on Hermes in 1969-70. In the views of Ministry of Defence, Dennis Healy, the carrier could operate the most modern aircraft, but in too small numbers to be effective.