In early 1986, BAe recognised that Royal Ordnance was having difficulties delivering the missile's motor, named Nuthatch, and began to consider alternatives. Royal Ordnance's solution to the required burn-loiter-burn characteristic of the engine was complex. In July 1987, BAe, by then the owner of Royal Ordnance, replaced the Nuthatch motor with a lower risk motor designed by Bayern-Chemie. BAe's GB£200 million contract for the missile was renegotiated with the price increased to GB£400 million and delivery pushed back from 1988 to 1990. The radar seeker was made by Marconi Defence and Space Systems (GEC) at Stanmore.