Would 26-knot battleships force 32-knot battlecruisers?

Would a 26-knot British battleship force battlecruisers to aim for speeds above 30 knots?

Yes; roughly 32 knots might be needed so battlecruisers retain a useful speed margin over the new battleships.

Battlecruisers might need roughly 32 knots if battleships begin the dreadnought era at 26 knots. The scouting type needs a meaningful margin to control contact and escape from the battle line, not merely a different label. Achieving that speed in 1907-08 would pull machinery and hull development forward years before navies historically fielded such ships. German battlecruisers that accepted speeds around 26-28 knots would be especially vulnerable because some older enemy battleships could match them.