On Wed, 16 Apr 2014 16:41:31 +0000, Tim Streater wrote:

Of course, it's also the reason that coalitions, and the electoral
systems that tend to produce them, are a very bad idea, because under
such systems the chances of a party having to be held to its manifesto
are slight. So they can say, write, and promise what they like.

Not necessarily.

Party A's values and priorities are known.
Party B's values and priorities are known.

So the coalition document will tend towards a compromise - somewhere
between Party A & Party B's manifestos. Some of A's policies and
intentions will get through, untouched, where B aren't heartily against
them, and vice versa. Where both are entrenched, then either a mid-point
that both can agree on will come forth, or it'll get parked.