I have done a research on Wrens and here is the information:

• Bird family: Wrens
• UK conservation status: Green
• Scientific name: Troglodytes troglodytes
• Protected by The Wildlife and Countryside Act 1981

The wren is a tiny brown bird, although it is heavier and not as slim as the even smaller goldcrest. It is dumpy, almost rounded, with a fine bill, quite long legs and toes, very short round wings and a short, narrow tail which is sometimes cocked up vertically. For such a small bird it has a remarkably loud voice. It is the most common UK breeding bird, although it suffers declines during prolonged, severely. What they eat: Insects and spiders.

• Measurements: Length: 9-10cm
• Wingspan: 13-17cm
• Weight: 7-12g
• UK breeding: 8,600,000 territories
• Feather colour: Brown Cream/buff
• Leg colour: Brown Pink
• Beak: Black Short Curved Thin
• Natural habitats: Woodland Farmland Heathland Urban and suburban

Source: https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/wren/