Where posting letters takes first class effort: Royal Mail mystery as official post box suddenly appears 10ft up motorway bridge concrete support Post box appeared embedded where the M54 crosses A442 in Shropshire Royal Mail has no idea how it got up there, so it could be a piece of art Britain's 115,000 Royal Mail post boxes are meant to be in places where communities can easily slot in a letter. But residents of Telford in Shropshire have been left scratching their heads after one appeared suspended 10ft in the air on the side of a motorway bridge. Motorists first spotted the mysterious box as they travelled to work this morning, and is not the first time such a bizarre sight has been noted after a similar occurrence in Berkshire. The bright red letterbox - which has baffled residents and postmen alike - is embedded in the concrete wall where the M54 crosses the A442. It must be for long letters: A Royal Mail post box has appeared embedded into the concrete of a motorway bridge near Telford Is this the best excuse for not sending Christmas cards? The red letter box helpfully sets out collection times and others nearby It helpfully informs customers of a later collection at another nearby pillar box but Royal Mail bosses have no idea how it got there. Post modern art? Royal Mail are unsure how the post box got there, raising speculation it is an art project People in the area have been left wondering how the traditional box was installed next to the busy dual carriageway without anybody spotting those responsible. Student Adam Washbrook, 17, said he did a double-take when he first saw it. He said: 'I was walking past and it caught my eye. 'I couldn't believe it, how on Earth did they even get it up there?' Another passing motorist added: 'I couldn't believe it when I first saw it. I had to go back and check and it is a realistic letter box stuck on to the concrete structure somehow. Unless the Royal Mail has gone off its collective rocker - you would need to be 10ft tall to post anything - it must some sort of prank. Not even Peter Crouch could reach that. 'Or maybe it's a reference to their rising share prices.' Villagers in sleepy Sonning-on-Thames, Berkshire, got a similar surprise in September this year when a similar letter box was attached to a river bridge. The installation, which could only be accessed by boat, was suspended 1m above the water level of the River Thames. Flashback: This similar red letterbox has appeared recently on a bridge in Berkshire over the Thames