Monochromatic Schur triples in randomly perturbed dense sets of integers

Given a dense subset $A$ of the first $n$ positive integers, we provide a short proof showing that for $p=\omega (n^{-2\mathrm{/}3})$ the so-called {\sl randomly perturbed} set $A\cup [n{]}_p$ a.a.s. has the property that any $2$-colouring of it has a monochromatic Schur triple, i.e.\ a triple of the form $(a,b,a+b)$. This result is optimal since there are dense sets $A$, for which $A\cup [n{]}_p$ does not possess this property for $p=o(n^{-2\mathrm{/}3})$.