Just in case you didn't all know this, the RB162 was originally designed by RR for use in VTOL civil airliners. The multiple small engines were intended to give adequate redundancy (compared with the single vectored thrust engine in the military Harrier).
I designed and stressed the turbine blades, and still retain the broken bits from the previous design of blade (it had failed on the test bed). Some test bed failures in those days at RR were pretty dramatic.
Of course civil VTOL never happened, so the Trident application was a welcome use of a redundant design.