Question About Front Design On Br Loco

I dont understand which one comes earlier :
the yellow headbox

or the black box?


And which year BR started adding
this

and this?

 

If AL1-4 originally support LNER 15kv ,
even now , the class 86/87 has the ability to support 15kv?

 

High Intensity Headlights were introduced in 1983
Yellow Headcode boxes came first
Jumper Cables most likely came in the 70s or 80s

 

They never supported the 1500v DC system. It was only the Woodhead trains (classes 76, 77 and 506), Altrincham trains (Class 505), Shenfield Metro (class 306, later rebuilt to use 25kv ac) and Tyne and Wear Metrocars that supported it.