It appears that from time to time boats get stolen but most get recovered. A web site is dedicated to finding them. Here is the link for narrowboats.
The owner has given the following details:
They have requested to email them at findmyboat@outlook.com
This boat was stolen from Mercia Marina around the 9th of July. The boat may be moored in a quiet area or it may be travelling. The boat was not sign written. It is 50' NB cruiser stern in dark blue, maroon and cream stripes and a cream roof. It has a distinctive metal curved stern. It has the Stenson logo SB laser cut into the steel. The boat has a tv aerial roof mounted, flat white plastic disc type with a telescopic aerial. The fenders are three solid tubular double lengths which trail in the water, Brass coloured window framing. Lounge at front - Solid fuel stove right at front on port side, it has a tiled red, white and blue fireplace in the lounge corner port side at the front. Cruiser stern with HIN number which is, GBMCCSC438E414, stamped into it. The boat MAY have changed colour and sign written.
They have requested to email them at findmyboat@outlook.com