The state of the tyres has led to suspicions that they may have been cut off old vehicles going for scrap, as scrapyards often pay less to dealers if they have to remove a vehicle's tyres before cutting it up.

Argyll and Bute Council's local environmental warden Ailsa Cunningham was informed, and Beachwatch Bute's island beach ranger Sandra MacMillan removed the tyres from the scene and took them to the council's landfill site at Westlands on the outskirts of Rothesay later that day.

Beachwatch Bute chairman Billy Shields told us: "We think the dumping may be the work of unlicensed scrap metal dealers who may have been going round houses on the island offering to uplift old cars and other bits and pieces - they'll know they can't send them on to scrapyards with the tyres still on without a financial penalty.

"I understand this has been happening elsewhere in Argyll and Bute as well, so it's not just a Bute problem, but people should still be wary of anyone offering to come and uplift any scrap vehicles they may have."

Friday's trip to Rhubodach wasn't Sandra's only unusual call-out this week: she also headed to St Ninian's Bay on Monday morning after a call to police the previous evening reported two large mounds of unknown grey, gelatinous material washed up at the high water mark.

Billy Shields, who, along with The Buteman, was also present at the scene, said he thought the blubbery material was most probably the flesh or fat of a basking shark or some type of whale.

There was, however, no sign of a carcass, which made it difficult to identify for certain whether it was a whale or a shark.