How to Convert any Battery train to Wireless RC

I purchased off Ebay this Catepillar Diesel Train set for only £10 a real bargain , only trouble was it was for my 3 yearold Granddaughter and the operation of it was difficult for her. To switch it on you had to press the red light on the top of the cab and to stop it the same , however she couldnt do it without knocking the train of it's rails . So Granddad put his thinking cap on ( as Granddads do lol ) and decided the best thing to do was turn it into a wireless remote , It was far easier than I thought it would be watch the video to see how .