Oddly, Merlin Gerin don't do a 13amp to my knowledge, but do have some odd sizes below 10amp.
1, 2, 3, 4, 6, 10, 16, 20, 25, 32, 40, 50, 63.
http://www.ebay.co.uk/itm/MERLIN-GE...UK_BOI_CircuitBreakers_RL&hash=item41557ec644
http://www.ebay.co.uk/itm/300900417315?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
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