Teaser 2869: Cubic savings

From The Sunday Times, 17th September 2017 [link]

In 2009 George and Martha had a four-figure number of pounds in a special savings account (interest being paid into a separate current account). At the end of the year they decided to give some of it away, the gift being shared equally among their seven grandchildren, with each grandchild getting a whole number of pounds. At the end of the following year they did a similar thing with a different-sized gift, but again each grandchild received an equal whole number of pounds. They have repeated this procedure at the end of every year since.

The surprising thing is that, at all times, the number of pounds in the savings account has been a perfect cube.

What is the largest single gift received by any grandchild?