This photo shows eleven apple varieties grafted on to a single rootstock to produce an "instant espalier".
The top one is a Lady Williams which should keep till at least September and the next one down is a Christmas Apple which ripens just after Christmas.
The other 9 varieties should give apples from when the Christmas Apple finishes to when the Lady Williams starts, meaning you will have apples from 9-10 months of the year from a section of wall or fence.
A normal espalier take perhaps 4-5 years to develop its laterals in the right place and only one variety. A reason why you should learn to graft: you won't be likely to find one in the local nursery.
The Christmas Apple was an old tree at an abandoned home on a farm at Stockdale and the original tree has died - lucky we saved it.