In the U.K. the xfmr primaries are always wired phase-to-phase, since our MV/HV never distributes a neutral.

3-phase xfmrs and 240/415 Y local distribution is the norm for anywhere where there are more than a few houses, but where single-phase spurs are run for remote rural homes, the HV is always run as two phases:

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Xfmr above is 11kV primary, 240V secondary.