Eagle-eyed bus spotters have noticed a rather unusual addition to fleets driving around Leeds in recent weeks.
Pictures have emerged of a red, single-decker Transport for London (TfL) bus on roads across the city over the past few days, leaving passers-by perplexed.
It's not simply a case of a confused driver taking a 200-mile detour though.
Instead, it's all part of a trial by First Bus, who have confirmed to LeedsLive that they are using the bus to trial electric vehicles.
The TfL bus is fully electric and much cleaner than most buses currently on the road - but it is not actually in service and will not be carrying any passengers throughout the two-week trial, which ends this week.
Leeds is the only place in the entire country where First are trialling the TfL electric bus, although a number of similar schemes are planned in other locations.
York will soon be trialling electric double-decker buses, while vehicles powered by bio-gas and hydrogen are being tested in Bristol and Aberdeen respectively.
First Bus are currently in the process of upgrading their fleet of buses in Leeds, so they comply with Euro 6 standard vehicle emissions.
The companies new buses emit much smaller amounts of harmful nitrogen dioxide and they will not incur £50-a-day fines when the Clean Air Zone comes into effect - likely in 2020.
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