have owned a few 31's over the years, different years came with different colours.

none of this matters very much, whats important is that it has a switched earth, not positive, I'm not 100% certain, but this is done for safety if anything dodgy happens to wiring. never made much sense to me.

Otherwise its a variable speed pumno, it has a signal wire to vary the speed, doesnt hurt to have it full blast all the time, but may reduce pump life.