The couple have been together for almost two years and reports recently suggested they might be about to move in with each other after Cressy was given the seal of approval from Royal security guards.
Harry also kept it casual with a blue check shirt and jeans.
According to The Metro, Cressida playfully heckled Prince Harry when he took to the stage and joked and apologised to anyone expecting another famous Harry (Styles, fyi)
It's a rare public display of affection from the couple who were also pictured together earlier in the week as they left The Ivy.
Let's look back at Cressie's style...
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