There is a grapefruit tree growing outdoors, and which produces fruit, in the Chelsea Physic Garden, located in London.

It has been nick-named 'Aunt Queenie'.

The tree is located in a sheltered corner up against a brick wall under the protection of a large olive tree, and produces regular crops of large yellow fruits that hang for months on its branches.

A couple of possible factors that may be contributing to it being able to grow so far North: it is located in the center of a large city which probably has an effect on the localized climate, the garden is located next to the Thames river which may be having a moderating effect on the nearby temperature, the tree is growing in the corner of a sheltered walled garden. The fact that it was grown from seed and is not grafted onto a different rootstock might also be making the plant more vigorous and resilient to the cold. Since it is a white grapefruit, the variety it was sown from was most likely Duncan or Marsh, which are a bit more hardy than other common grapefruit varieties.