Heat 1 litre of water to 90–95°C. The temperature management is the same principle as the Iced Tea Lemonade preparation — black tea at 100°C extracts harsh tannins rapidly; at 90–95°C the pleasant theaflavins and thearubigins that provide black tea's characteristic warm, structured, lightly tannic backbone extract cleanly within 3 minutes ahead of the harsh fraction. Add 8 or 9 black tea bags — 8 for a clear tea presence; 9 for a slightly more assertive tea backbone against the peach's aromatic softness. Steep for exactly 3 minutes. Remove all bags simultaneously without squeezing — the concentrated, most astringent liquid held within the bags produces the specific harsh note that the recipe brief's squeeze-prohibition addresses. The 8–9 bags in 1 litre are calibrated for a cold-drink extraction context — stronger than comfortable drinking-strength to account for the subsequent 1.8–2.2 litre dilution. The brief's note ("not 9 bags in 500ml") is specifically about the difference between a concentrated extraction that will be diluted to crowd scale versus a genuinely bitter concentrate that cannot be moderated by dilution.

While the tea is still hot immediately after bag removal, add 100g of light brown sugar. Stir until completely dissolved — the tea's residual heat is sufficient and specifically more efficient than dissolving the sugar at lower temperatures. The light brown sugar's warm caramel-adjacent molasses character dissolves into the hot tea and integrates with the theaflavins' warmth, producing a sweetened tea base with a more specifically complex, warmer sweetness than white sugar would provide at the equivalent quantity.

Allow the sweetened tea to cool for 5–10 minutes uncovered — until the steam has significantly reduced and the liquid is warm rather than actively hot. The temperature target for the peach addition is approximately 70–75°C — warm enough for efficient peach aromatic extraction but specifically below the temperature that converts the most pleasant lactone aromatic fractions to the cooked-peach register. Add the thinly sliced skin-on peaches and the lemon zest simultaneously. Cover and allow to steep for 10–12 minutes. At this temperature range over 10–12 minutes, the peach's γ-decalactone and δ-decalactone aromatic compounds extract into the warm, tannin-containing tea medium efficiently — the tea's slightly astringent medium specifically producing a more integrated peach-and-tea aromatic result than plain warm water would. The lemon zest's volatile aromatic oils provide a specifically clean, bright citrus bridge between the tea's warm tannin character and the peach's soft, warm, lactone-driven fruitiness — the same bridge function served by lemon zest in the fruit syrup crowd preparations. At 10 minutes taste the extract and assess the peach presence: if the peach is vivid and aromatic, strain immediately. If still mild, extend to 12 minutes. Do not extend beyond 12 minutes — the cooked-peach character begins developing as the medium cools further and the heat-residual cooking continues.

Strain through a fine-mesh sieve, pressing gently but firmly on the peach and tea-softened fruit solids. The pressing extracts the final peach-tea aromatic liquid from the slices — press until the peach slices are noticeably thinner and the yielded liquid from pressing has substantially increased. Allow to cool completely.

Pour the cooled peach tea extract into the large pitcher. Add 1.8 litres of ice-cold water. Stir gently. Taste — the tea should be clearly present as the structural backbone, the peach clearly present as the aromatic primary flavour, and the lemon a background citrus bridge. If the tea is too assertive for the peach, more cold water (up to 2.2L) moderates the tannin character. Before finalising the water quantity, taste for sweetness: if the peaches were particularly ripe and the 100g of sugar is sufficient, leave as is. If additional sweetness is needed — a small amount of the remaining 20g of sugar dissolved in a splash of hot water and added to the pitcher. Refrigerate for 1–2 hours. Stir before serving. Garnish with fresh peach slices (prepared immediately before service) and lemon peel twists. Serve cold.