Captured trenches could be lost before help arrived

Was that the problem faced by the royal gardeners who captured a position?

The recalled unit is not confirmed. Troops could seize a trench and then lose it because information and reinforcements could not get through.

Alex recalls reading about palace gardeners who captured a position but could not tell others they held it. John Bull answers by explaining the wider problem of breakthroughs that could not withstand counterattack when headquarters lacked information or a route for reinforcement. Even a runner who reached headquarters brought information that was already old. Artillery could then prevent supporting troops from reaching the position. Tunnels helped create protected connections between the previous front line and the hoped-for new one; the exchange does not establish the gardeners' unit or confirm the recalled incident in detail.