1. Any project can be "on time" if you keep redefining the ISD.
2. A huge number of projects are delivered ahead of time, under cost and with exceptional performance by MoD. It is just that detractors don't like mentioning them. However, nor does MoD, as it raises the bar of expectation for those who deliver late, over cost and under performing kit. The latter are generally those who are promoted beyond their level of competence.
Next time you speak to anyone at 1 Star and above in DE&S, ask them to tell you about their 100 most successful projects. (In 1990 this was the benchmark for receiving a "Fitted for Promotion" marking to the second most junior grade in MoD(PE)). No, make that 10. No, one. Ah, don't waste your time.