Cracked Top On Fruit Cakes

[mikey4444]

I have made 3 of Boaty's fruit cakes, as prezzies but one of them has come out with a cracked top.

I know that the temp. is set properly, as I place a thermometer along side the cake tin, on the same shelf...its Gas Mark 3.

I weigh the ingredients out very carefully and use medium eggs.

I use the middle shelf in the oven and don't open the door to check too often.

Can anyone else think of what else I could be doing ?

[Buenchico]

Trapped air?
https://www.livestrong.com/article/424951-how-to-prevent-a-cake-from-rising-cracking-in-the-middle-while-baking/