Terry Casey posted
In article
k,
says...

As so often happens (apologies) having posted the question I almost
immediately found the answer:

K1 1.34 (c): If the stairs are 1000mm or wider: provide a handrail on both
sides.


https://assets.publishing.service.go...ds/system/uplo
ads/attachment_data/file/443181/BR_PDF_AD_K_2013.pdf

You also need to take into account who will be using them.

For example, I walk with a stck in my right hand so, if I'm
forced to use stairs, it is important to have a handrail on
the left in BOTH directions, irrespective of the width of the
stairs.

Of course the OP must also accommodate those who have no limbs and are
blind and deaf. So, rather than a stair, he must install a lift with a
fitted gurney, permanently staffed by a medically qualified attendant.

--
Evremonde