The problems are:
1. Commercial vehicle, (Mercedes sprinter luton van 311, weight and width and age ok). Not ours.
2. Over the height in the terms and conditions, - I would advise you all to check your dimensions in the small print as they may refuse to recover your vehicle if outside their limits. They wont check with you when you order/take the policy out, it's up to you to check it's suitable.
Have tried:
Green flag, ADAC, RAC, AA, and a couple of smaller companies. Also rang our Bank as Robmac suggested, AA cover, but again only for vehicles under 3 metres high, and non commercial.
Will ring the owner and see if he can get commercial cover, but dreading what the cost will be.
Thanks for all the replies/suggestions, keep them coming!