Houses 1-8 have conventional full-height garden gates. These were originally made of oak but replacements are often treated softwood.
Houses 9-25 have custom gates designed by the architects. These have vertical slats with carefully-chosen dimensions that allow some visibility but control the sight-lines through the gate. If replacing a gate it is very important to get this right. See Cris’ document for details:
Cedar Chase Garden Gates – houses 9 to 24
Locks for garden gates
The structure of the 9-25 gates is quite thick around the lock, and there is a risk of needing a very long key. This can be avoided by using a Euro-profile mortice deadlock with an asymmetric cylinder (one that sticks out further on one side than on the other). Make sure that the lock has enough ‘backset’ to allow you to turn the key easily: measure from the edge of the gate to where you want the keyhole to be.
For the lock cylinder, you need to measure from the centre-line of the lock to the face of the gate on each side. Better lock suppliers have a range of cylinders to choose from, e.g. this range from Ironmogery Direct. Look at the ‘Split Size’ option on the left-hand menu. Cylinders start at 30mm + 30mm and go up to about 45mm + 60mm.
You could consider trying to get a cylinder made to match your house key, but that might be difficult. You could also consider changing all the cylinders to use the same (new) key. GCD Security in Maidenhead are very good so it is worth talking to them if you want anything out of the ordinary.