Michael wrote :

Excuse my ignorance, but what are birds eye chillies? and can I
obtain them in any large town or city? I live near Leeds

You should be able to buy them in any Asian grocers. They will not
probably be labelled as "birds eye chillies" but that's what they'll
be. They might be labelled "extra hot chillies". They are dried,  small
(15-25mm long by 4-5mm wide), red and pretty hot!. You'll recognise them
when you see them. There's a picture on the Chilli Willie's Web site in
the Spice Emporium.

I enjoyed making and eating your quick curry sauce

Great! Glad you liked it.