1. You certainly would have a good cause of action to get your money back. The relevant terms of the auctioneer do not override the mandatory consumer law provisions which are applicable in England whereby all items sold must be of merchantable quality and correspond to description. Here the items were not of merchantable quality as they had parts missing and did not accord with their description as "new". So you can successfully sue the Bristol auctioneer in a court in England and recover your costs. The auctioneer's clause that no guarantee is given is not operative to prevent the application of these standard clauses which are implied into every contract of sale of goods. It makes no difference that you are based in Scotland. The law still applies to the goods sold to you by the seller in England.
Just want to make sure the advice is valid when goods are being purchased in the execution of a business rather than for personal use. All items I purchase are ultimately re-sold on ebay for example. The items that are subject to the dispute were delivered directly to the end user from the supplier at it was the end user who first reported the issues with the products. I am making sure I have reasonable grounds to take action based on the false descriptions of the items I bought.
2. These implied terms are no dependent upon your being a consumer. They apply to business dealings as well. It makes no difference that you were an intermediate seller in a chain which ultimately ended up with the EBay buyer. The same warranties and implied terms apply and you can sue for damages. However, be aware that you should inspect or get an agent to inspect the goods as delivered to ensure there actually was the problem with them the EBay buyer is asserting.