Slippery Silica Mining Corporation entered into a contract with Highgrade Transport Company to haul its ore from its mine to a railway terminal, a distance of some 50 kilometres. The contract called for the hauling of approximately 60 tonnes a week for a one-year period. Because Slippery Silica Mining Corporation was a very small company, Highgrade Transport requested that Wilson and Rose, its two principal shareholders, personally guarantee the payment required under the terms of the contract.

In due course, Wilson and Rose provided a written guarantee of payment. It bore their signatures and that of their witness, Sheila Drew, a young woman who worked in their office as a receptionist and typist. The guarantee was not under seal, so the owner of the transport company immediately drove down to the mine office to have the two owners affix seals to the document.

At the mine office, the owner of the transport company met Sheila, who informed him that both Wilson and Rose were away for the day. When he told her the purpose of his visit, she took a box of red legal seals from her desk and offered them to him with the comment, "I don't think they would mind if you put on the seals yourself."

The owner of the transport company took two red seals and affixed them next to the signatures of Wilson and Rose on the guarantee. Then he left the office with the document.

Some time later, the mining company fell into arrears in its payments under the contract. The transport company notified Wilson and Rose that it intended to look to them for payment under their guarantee.

Discuss the issues raised in this case and determine the legal position of the parties.