Another reply from DVSA re MOTs, they advised to contact the DVLA again with regards to the speed question...
So if you have a fully converted van my take is on it is that you should be good for a Class 4 MOT.
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Thank you for your email enquiry dated 1 November 2019, concerning the above.
There is often confusion between what is tested as a 'Motor Caravan' and what is tested as a 'Living Van'. They are defined as follows;
Motor Caravan
A 'Motor Caravan' has installed equipment and facilities neccesary for the vehicle to provide living accommodation and which only carries goods needed for the purposes of residence in the vehicle (e.g. sufficient food for expected length of holiday, cycles, surfboards etc). They could even carry something like a scooter, if is used for the purpose of residence in the vehicle (the scooter could be used for shopping because of the size of the caravan). Regardless of weight, they would come under Class IV.
Living Vans
These are vehicles used for carrying goods which are NOT needed for the purposes of residence in the motor caravan (e.g. a motor caravan used as a van to carry quantities of goods from one place to another, or a motor caravan which also has an area set aside to carry horses). These vehicles can be tested as Class IV, VII or HGV depending on the Deisgn Gross Weight.
You will need to address your enquiry regarding information on the V5 to the Driver and Vehicle Licensing Agency (DVLA).
The DVLA Email Service can be found
here
Telephone: 0300 790 6801 for drivers queries.
0300 790 6802 for vehicle queries.
I hope this information has assisted you with your enquiry, but if you have any further questions please do not hesitate to contact us again.