If you like Bell's, £16 is a pretty good price for a litre bottle. Occasionally, £15 elsewhere, but not at the moment AFAIK.
However, there are lots of £20-off vouchers available for NEW Ocado users.
For example, Quidco have a code for £20 off an £80 shop. So, if you buy 5 bottles, that's £80, reduced down to £60. (£12 per litre bottle.)
Plus £6 Quidco cashback, if it tracks.