Cambridge Grammar of English Hardback with cd-rom a comprehensive Guide

No conditional subordinator

Conditions can also be conveyed without any overt conditional subordinator,

often using and, especially in informal spoken language:

We’d better not be late. They’ll leave without us.

(They’ll leave without us if we’re late.)

[parent to misbehaving child]

Do that again 

and I’ll get very angry.

(If you do that again, I’ll get very angry.)

Buy three CDs 

and get one free.

(If you buy three CDs, …)

LINKING WITH THEN

457

Then

is often used to link a main clause following a conditional to add emphasis:

[from an Oxford City Council tourist brochure]

If you are visiting Oxford, then why not take the opportunity to visit The

Oxford Story – a museum of Oxford life down the ages?