Can anyone tell me what this is? It's in a front garden in North London. Seems to survive with little care from what I've seen.
This is Prunus laurocerasus, common name cherry laurel. I wouldn't recommend it frankly - it gets 25 x 25 feet eventually, although its a good large shrub/small tree for shady areas. I note the wall behind it is tipping over - this shrub produces lots of large and deep woody roots, so it really shouldn't be planted close to any structure like a wall.
UPDATE: There has been an alternative ID suggestion of Magnolia grandiflora; on closer inspection of the image, that is a possibility, though I'm not seeing the density of hairs beneath the foliage one would normally expect. There are also no signs it produced flowers last summer/autumn, although they don't usually flower much before 12 years old anyway. In the UK, these can reach a height of about 12 metres, with a spread of 8 metres. The flowers are white, fragrant and cupshaped; Prunus laurocerasus, on the other hand, produces upright 'candles' of small white flowers, usually in May.