Didn’t Heljan produce the O Gauge Hatton’s A4 locos?
They had terrible feedback in general.
Underpowered with only one motor, motors burning out, loose bits in the box, valve gear back to front, quartering problems etc.
Have no experience myself, just comments that I have seen online several times.
Think they were £750 GBP when new, but Hatton’s sold them off around half price in the end.
Rails of Sheffield had six of them second-hand, varying from £450 GBP to £500 GBP, about two weeks ago, and four have already sold.