Hi Claire,
Click on Search England and Wales 1837 - 1983. I found young Master McFarlane with the details Apr-May-Jun 1916 (both from and to as I have already ascertained that he wasn't registered in Jan-Feb-Mar 1916), McFarlane George. Click on Search. This takes you to: McDonough, Peter to McGlasham, Joseph. Click on View. This will take you to page 125, Births Registered in April, May and June 1916, McD - McG. He is towards the bottom of the first column, starting McFarlane Doreen, then Edna V., then George A. It costs 1 unit (10p or less, depending on quantity of pre-purchased units). I hope he's the one you're after.
Good luck.
Dimps