The Blue Terrance Trunki is curently £21.95 on Amazon
Link here: http://www.amazon.co.uk/Trunki-Terrance-Ride-on-Suitcase-Blue/dp/B001A2H050/
He is £29.99 in Mothercare, so if you ring them on 0844 875 5222 (8am to 8pm Monday to Saturday and 9am to 5pm on Sundays)
and tell them you want to price match the amazon price, they will also send you a £10 mothercare gift voucher as part of their price promise deal! I would remind them about the voucher, and they say "5-7 days delivery" but in my experience they always come next day recorded delivery.
So your getting Terrance for £21.95 and a free £10 voucher thrown in! Hope this helps someone :)
THOUGHT THIS NEEDED AN UPDATE:
Thanks to so many people taking advantage of this fatastic deal its become apparent that you can now get any trunki from amazon for around £24.95, price match it and get your voucher. Mothercare are well aware of the deal and when you ring up and request to price match a trunki, most staff know the prices of amazon by heart already! Also as amazon do free delivery, so will mothercare! so wherever you find it, try and get free delivery.
22nd June 2011 - THIS STILL WORKS!! Order to collect at store if they try and charge you for delivery. Wait till you get the gift voucher in the post before collecting your item, then you can collect and spend your freebie at the same time :)