Retail buyers can't do it with their own accounts, but you can...

Retail buyers can't do it with their own accounts, but you can easily call a broker to do it for you. I could literally call a broker right now and organise for them to do it for me tomorrow, at a competitive brokerage fee. You could too. I know people who do it when buying or selling large quantities, and if it had the effect you're saying, no one would ever do it, because it would be self-defeating. It literally does happen, I literally know people who do it, it's not that unusual and you can easily do it yourself with the assistance of a broker who provides this service, as many do.

Actual manipulation has clearly been occurring on TNT, but not everything which isn't a typical retail trade is manipulation or somehow nefarious.

Almost none of those trades today moved the price. When you see a tiny trade which does move the last price a pip and it comes immediately after a large trade (particularly if it consistently comes after every large trade and it's always on the opposite side of the spread), yes, that's blatant manipulation, and sure, you see that often, and yep, I've seen that on TNT, but it wasn't happening today.

Examples of the most aggressive manipulation I've seen on TNT was being carried out when the price was clearly starting to run, and big sales were going through to wipe out buy depth as it came out, strategically to knock out a wall then just a touch of the next level down (no genuine seller would do anything like that - a seller wanting to sell that much would ensure they didn't quite take out the entire buy wall each time the made another sale).