[steam for ever]

I've only ever seen one class 73, and now I'm not sure where it was. Was there one at railfest this year?

Anyway, it has been arguably one of the most successful classes first generation diesel locomotives, and they are still around on the national network in significant numbers.
Their longevity has been due to their ability to run either off a third rail DC power supply, or by means of an onboard engine, and also that there has been nothing to replace them.
As fantastic as they are, they are getting on for 50+ years old, which exceeds their intended life span quite considerably.

Are there any plans for a new locomotive of this type?

I have noticed that since privatisation, classes of loco and multiple unit have ceased to be replaced as they should, and the result is an ageing fleet which is becoming more difficult to maintain.
I like the old classes such as 47 and 37, but really it would help firms in this country such as Wabtec Brush and Hunslet by generating new locomotive orders.
Sureley a new British electrodiesel could be designed an built here, and be the envy of the world?