Checked the post office tracking later, and it once again said it was out to be delivered. Unfortunately it is the one day a week when my parents go shopping, so they weren't in to collect it. When I checked the status later it said they had tried to deliver, and that I could collect it from the sorting office.
I had a sleepless night as I thought it was too quick from it having been sent to the High Commission, but I picked the passports up this morning, both containing 6 month multiple entry visas.
I've checked the VFS tracking for my passport and it says:
Your application is processed and sent to the offices of the Indian High Commission in the UK for further assessment. Please check our website
http://www.in.vfsglobal.co.uk for further information on 'Processing Times'.
I think one piece of advice I can offer, is, don't worry too much about the status on the website, they clearly don't update it very often.
Passports were signed for last Wednesday, and posted yesterday (Thursday). When you take in to account one Indian holiday and one weekend, that's only 6 working days. Quite impressive.
And now........................ relax.