Ha... my "remote-voltage-sensing-fu" is working well :)

2x15 V: VB 1,0/2/15 from Farnell £2.07p+VAT but min order value £20

Same from RS £3.74+VAT, free p&p but out of stock till Oct.

Same from CPC £ 3.18 inc VAT + P&P and in stock. Note: this one has 2 x 115v primary so may need minor mod to pcb?